Watermark a PDF in Adobe Acrobat
1. Acrobat can add watermarks to any PDF, either on top of the text and images or underneath. These can be made visible only onscreen, only on printed copies of the document or on both. In Acrobat 8.0, load your file and click Document, Watermark, Add.
2. The watermark dialog box previews the current page on the righthand side and gives options for its design on the left. Start by typing in the text of the watermark in the Text panel, or browse to a file stored on your PC that contains this text or an image by clicking File.
3. Select a font colour for your watermark using the button below the Text panel. Pastel colours are always a good choice, allowing the document itself to remain readable. Slant the text using the buttons under Appearance; this will allow the mark to take up more of the page than if it were horizontal.
4. If the document contains text and graphics, your watermark may need to be placed above the page furniture. Set the opacity below 100 percent, however, or readability will suffer. Use the Opacity buttons and slider under Appearance to achieve the right balance between security and readability.