I have copied the post from : www.planetpdf.com so all the credit goes to the OP.
“There are lots of reasons you might want to apply a watermark to your PDFs, either on the page, document or archive level. For the purposes of this tip, let’s take the example of a document that needs to be reviewed by a small team before being updated and finalized.
You create a PDF version of your draft, and want your readers to be able to tell at a glance that this is not the final document. One easy way to accomplish this is to add a “Draft” watermark to each page using PDF software such as Adobe Acrobat or Debenu PDF Tools Pro. The following sections run through how to complete this task in Adobe Acrobat XI and Debenu PDF Tools Pro, respectively.
Adobe Acrobat XI
- Select Tools > Pages.
- Under the Edit Page Design heading, select Watermark > Add Watermark.
- Configure the desired watermark settings (see image below for a sample).
- Click on Page Range Options and select the desired page range.
- Click OK.
- Click on Appearance Options and check the appropriate boxes.
- Click OK.
- Click OK again to apply your watermark.
Debenu PDF Tools Pro
While Acrobat is certainly the best known software for manipulating PDFs, it is not the only option. It’s actually possible to apply the same types of watermarks without needing Acrobat by using a standalone application such as Debenu PDF Tools Pro. Here’s how to add a “Draft” watermark similar to that produced by Acrobat after following the steps outlined above:
- Select Tools > Stamps.
- Double-click Text Stamp.
- Select Text.
- Type the desired text (e.g., “Draft”).
- Set the desired opacity (e.g., 30%).
- Select Font.
- Configure the desired font properties (e.g., set font size to 100).
- Re-size the watermark box in the stamp preview if appropriate (e.g., to ensure that the watermark will fit on the desired number of lines).
- Select Position.
- Configure the desired position properties (e.g., 0 from top and center, 315 degrees clockwise rotation).
- Select Pages.
- Configure the pages to be stamped (e.g., set to “All pages”).
- Click OK to apply your watermark.”