In another thread on here (I can't find it now, but it was dealing with bumper rules), someone postulated that a perfectly circular robot, rather than having a single edge on their frame perimeter, would actually have an infinite number of exterior vertices. Under that interpretation, any appendage extending over the frame perimeter would be crossing multiple edges.
As far as inspecting/reffing this rule... there's nothing in inspections that should be affected by this rule. It's perfectly legal for a robot to have as many appendages as they want, and to have them on one side or multiple sides. They just can't extend them all at the same time. So it really comes down to reffing. Refs are going to follow a rather simple rule in calling penalties for this - if it looks like multiple appendages, then it gets penalized. Here in Minnesota, we have 60+ teams at each competition. It's going to be next to impossible for the refs to remember which robots have multiple appendages on the same side, versus which ones have a single appendage that just looks like multiple appendages.
So save yourself and the refs some headaches and make things obvious.
Edit: found the post referencing circular designs:
http://www.chiefdelphi.com/forums/sh...2&postcount=43