Using Ghostscript to add page numbers via batch

Others have given good advice in comments to suggest a file with feedback such as this potential single run.cmd. It should not work in full, but will produce a false output, and allow you to see the errors.

NOTE GhostScript requires case specific full filenames hence the use of %~f1" and %~f2"

@echo off

REM Check if the correct number of arguments is provided
if "%~1"=="" ( echo Usage: %0 input.pdf output.pdf & exit /b 1 )
if "%~2"=="" ( echo Usage: %0 input.pdf output.pdf & exit /b 1 )

REM Input and output files
set "INPUT_PDF=%~f1"
set "OUTPUT_PDF=%~f2"

REM Temp file for the page numbering PostScript
set "PSF_SCRIPT=C:\Temp\GhostScript\AddPageNum.ps"
    
REM Run Ghostscript to add page numbers
"C:\Program Files\gs\gs10.03.1\bin\gswin64c.exe" -o"%OUTPUT_PDF%" -sDEVICE=pdfwrite -dPDFFitPage "%PSF_SCRIPT%" -c "/Times-Roman findfont 12 scalefont setfont" -c "/showpage {showpage /PageCount 1 add def} def" -f "%INPUT_PDF%"

if exist %OUTPUT_PDF% echo Page numbers added to %OUTPUT_PDF%

Most likely output should be something along the lines of

Loading NimbusRoman-Regular font from %rom%Resource/Font/NimbusRoman-Regular... 3865264 2515446 1741192 449709 1 done.
Processing pages 1 through 1.
Page 1
   **** Error: Page drawing error occurred.
               Could not draw this page at all, page will be missing in the output.
GPL Ghostscript 10.03.1: Page object was reserved for an Annotation destination, but no such page was drawn, annotation in output will be invalid.

Page numbers added to C:\blah blah\output.pdf

So note the font mentioned is NOT Times which is a "surrogate" font name the attempted font will be Nimbus and if Times does show as forced it will be fontless (not embedded). What you need is

Loading NimbusRoman-Regular font from %rom%Resource/Font/NimbusRoman-Regular... 3865264 2515400 1915392 597811 1 done.
Processing pages 1 through 1.
Page 1
Loading NimbusSans-Bold font from %rom%Resource/Font/NimbusSans-Bold... 4025408 2714730 2136536 804225 2 done.
Page numbers added to C:\blah blah\output.pdf

with a report with embedded font

This is done by remove all those poor external directions and simplify down to:-

"C:\Program Files\gs\gs10.03.1\bin\gswin64c.exe" -o"%OUTPUT_PDF%" -sDEVICE=pdfwrite -dPDFFitPage "%PSF_SCRIPT%" -f "%INPUT_PDF%"

And provide a fuller modern AddPageNum.ps so from a similar answer use along these lines.

globaldict begin                %% Make globaldict the current dictionary
currentglobal true setglobal    %% We need to make the VM allocation mode for the dictionary global
/My_working_Dict                %% Create a name for our dict (choose something unique)
10 dict                         %% create a 10-element dictionary
def                             %% def takes a key and value and puts them in the current dictionary
setglobal           %% put the VM allocation mode back
globaldict /My_working_Dict     %% Get the dictionary from globaldict
get begin                       %% make our working dictionary the current one
/PageCount                      %% Make a name for our counter
0                               %% 0, this will be the initial value
def                             %% define PageCount as 0 in the current dictionary
end                             %% close the current dictionary (My_working_Dict)
end                             %% close the current dictionary (globaldict)

<<
  /EndPage {
    2 ne {
      0 0 0 setrgbcolor
      /NimbusSans-Bold 12 selectfont
      72 36 moveto
      (Page ) show

      globaldict /My_working_Dict get %% get My_working_dict from globaldict (leaves My_working_dict on the operand stack
      dup                             %% duplicate the dictionary reference
      /PageCount get                  %% get PageCount from the dictionary on the stack
      1 add                           %% add one to the count
      /PageCount                      %% put the key on the stack
                                      %% stack now holds << >> int /PageCount
                                      %% where << >> is a reference to My_working_Dict, int is our new value for PageCount, and /PageCount is the key name we are using
      exch                            %% swap the topmost two stack items
                                      %% stack is now << >> /PageCount int
      put                             %% puts the top two items on the stack into the dictionary which is third on the stack.
      globaldict /My_working_Dict get %% get My_working_dict from globaldict (leaves My_working_dict on the operand stack
      /PageCount get                  %% get PageCount from the dictionary on the stack
      256 string                      %% Temporary string to hold the count
      globaldict /My_working_Dict get %% get My_working_dict from globaldict (leaves My_working_dict on the operand stack
      /PageCount get                  %% get PageCount from the dictionary on the stack
      exch
      cvs                             %% Convert the top object on the stack into a string, storing the result in the second object down, whic must be a string
      show                            %% draw the string on the page using the current colour and font.
      true
    }
    {
      pop
      false
    } ifelse
  }
>> setpagedevice