Create a simple hyperlink to the re-useable document you'd like to share via your site like this...
Replace the "XYZ" with the reference number of the re-usable document. (Use the "nofollow" attribute so search engines won't crawl the link!)
You can get the reference number of the re-usable document from the address bar as if you were sending it for signature.
Here's a sample HR form we're hosting on this blog as a demonstration. Try the Sample HR Form