OK, I figured it out. Even though RamDisk was listed in the contributed library, there wasn't anything in it. I didn't know it before, but you can open a sketch and use "Import Library", to load the #include files into your sketch. That's a good test to see if the library is really included. Nothing came up when trying to load the #include files for RamDisk. It's all working now after restructuring the RamDisk files.
Gerry