#!/usr/bin/perl
use strict;
use warnings;
use PDF::API2;

# location of "Corporation" check box is:
#   173 pts from left, 660 pts from bottom

my $infile  = 'modified_fw9.pdf';
my $outfile = 'modified_check_corp_box_fw9.pdf';

my $pdf     = PDF::API2->open($infile);
my $page    = $pdf->openpage('1');
my $text    = $page->text();
my $font    = $pdf->corefont('Helvetica');
# prepare text object
$text->font($font,11);        # Set font to Helvetica, 11pt
$text->fillcolor("#000000");  # This is black
$text->translate(173,660);    # Text start location for Corp chk box
$text->text("X");             # Print "X" at 173,660
$pdf->saveas($outfile);
$pdf->end;