Got it! Your comment about it only being available made me pay closer attention to the tutorial. It was using "Circle Center Point", not Fillet. As soon as I made that selection, the key was available. Thank you! I feel a wee bit ignorant.

Sorry for my poor wording, What I'm actually trying to do is create a fillet at an intersection. Is there another way to select an intersection?

I'm running Mastercam 2019 and trying to complete MastercamU. When I was following instructions and went to use AutoCursor to merge two lines, that particular aspect won't respond. I click on the little black triangle to bring down the drop down menu, but nothing happens. So far, all other aspects of the software seems to be working, but I am very new to its use.