title: How to add an overlay/stamp to a PDF file in PHP?
body: <p>Does anyone know how to programmatically add a overlay or stamp to a PDF file in PHP? So far the best I've come up with is calling the <a href="http://www.pdflabs.com/tools/pdftk-the-pdf-toolkit/" rel="nofollow">PDFTK</a> library with the exec command. I'd prefer an actual PHP method if one exists.</p>