PDF Watermark tool will add watermark PDF in two different ways one text watermark and other is image watermark. With this watermark PDF you can insert hidden watermark to PDF documents and if any other person claims you than you can verify your document with this hidden watermark. This software provides many features like change position of text and image, set the transparency level of the watermark. You can try the trial version of watermarking software for this you don't have to pay. If you satisfy with the functionalities of software then you can buy full version of the software by paying $49 and start insert watermark into PDF. For more info you can visit: http://www.batesnumberer.com/watermark-pdf.html