in reply to Add watermark to a pdf
Can you show us the code you wrote using
PDF::Reuse? It looks like the prAdd method will
allow images to be added to existing pages.
You may also need to use something like ghostscript for that
level of PDF manipulation. There is a GSAPI module at CPAN that provides Perl access to the ghostscript API, but I've
never used it personally.
There's a PDF FAQ
here. Your question of how to add watermarks is
covered there but they suggest using this tool, which you have to buy.