I finally figured out how to post a picture, hosted on the RTF server, that appears as full size (not thumbnail).
Attachment 7236
Using the advanced editor, you need to edit your thumbnail in Wysiwig mode (A/A on top left), then double-click on your photo. An Image Settings box should open. Choose Full Size (or one of the other size options) and click OK.
ETA: I couldn't figure this out earlier b/c I wasn't able to get the Image Settings box to open in IE. I tried doing it in Chrome and it worked fine.
Jim