Add a 'DRAFT' watermark on pdf result of R markdown
<p>I would like to add some sort of 'DRAFT' watermark on the pdf result of an R markdown document. (I want to provide interim versions of the document, but I want the client to be aware that it's not the final version.)
I'm a beginner at R Markdown, and know almost no LaTex. I can't seem to find any instructions for doing something like this. Maybe some sort of template?, or a specific set of LaTex commands?  This would be across first or all pages, maybe colored red.
Thanks for any help.</p>