A-PDF Watermark (http://a-pdf.com/watermark/index.htm ) is a simple and useful program that allows you to batch stamp image and text watermark to PDF files. You can create your text watermark with file names, signatures, author and any unique words you like. And the watermark can set to be shown only in print. In other words, it hides when you view the PDF. With the help of A-PDF Watermark, you can make your unique PDF and protect your copyright.For more; http://a-pdf.com/faq/index.php?title=how-to-stamp-text-watermark-to-pdf-file-by-using-a-pdf-watermark .