The following URL may help

Also check the similar kind of post in perlmonks

When overprinting on an existing PDF, I tend to convert the input pages to a PDF form using the importPageIntoForm and formimage methods.

#!/usr/bin/perl
use warnings; use strict;

use PDF::API2;

my $infile = shift (@ARGV)
    or die "usage $0: infile outfile";
my $outfile = shift (@ARGV) || $infile.'paginated';

my $pdf_in = PDF::API2->open($infile);
my $pdf_out = PDF::API2->new;

foreach my $pagenum (1 .. $pdf_in->pages) {

  my $page_in = $pdf_in->openpage($pagenum);
  #
  # create new page
  #
  my $page_out = $pdf_out->page(0);
  #
  # Get the page size
  #
  my @mbox = $page_in->get_mediabox;
  #
  # Inherit mediabox
  $page_out->mediabox(@mbox);
  #
  # copy page as a form.
  #
  my $gfx = $page_out->gfx;

  my $xo = $pdf_out->importPageIntoForm($pdf_in, $pagenum);

  $gfx->formimage($xo,
                  0, 0, # x y
                  1);   # scale

  my $left_edge = $mbox[0];
  my $right_edge = $mbox[2];
  my $top = $mbox[3];

  my $txt = $page_out->text;

  $txt->strokecolor('#000000');
  $txt->fillcolor('#000000');

  $txt->translate(my $_x = ($right_edge - $left_edge) / 2 - 10,
          my $_y = $top - 15
      );
  my $font = $pdf_out->corefont('Courier');
  $txt->font($font, 12);
  $txt->text( 'Page: '.$pagenum );
}

$pdf_out->saveas($outfile);
[download]

Thanks so much! This works great for my use.