Thanks to everyone for pointing out Acrobat's watermark feature. I think it will be perfect for applying a watermark that can't be viewed until the document is printed.
The same client wanting the watermark wants his PDF documents to contain Sharepoint links to other docs (tiffs, Word docs, etc.) I told him that I THOUGHT I could create hypertext links in Frame (to avoid post-production re-work on the PDF) as long as I had the full path statement to the target document. I don't have any experience with Sharepoint. Do you know if my linking strategy will work or if there is a better way to do it? Carol