Short answer, "nrpc://852573710072208D/site.xml" should be "nrpc:///852573710072208D/site.xml".
Long answer, there is a bug in the Update Site template for Actions->Show URL. It leaves out a/.
If you open up any component doc, there is a "Install Instructions" button that will give you detailed instructions on how to add them individually.
Cheers,
Jo