I tried to find where QuiteRSS stores its files in OSX but could not locate them.
How would I migrate my installation over to OSX?
That worked! I copied these 4 over (from the data directory) to the Mac and everything came over -- including my filters.
Finally, bringing the quiterss.ini file over completed the picture, bringing over toolbars and other customizations. However the Windows fonts were too small for the Mac, so I had to revert those to the default font size from the Mac.