A coworker asked for help using radio buttons (on a choice field) to allow the user to trigger a rule on the new form. Using version 188.8.131.52, it did not work unless we changed the field to a dropdown instead of radio buttons. We tried using an earlier version of DFFS (184.108.40.206, released Jan 12, 2019) and the radio buttons worked just fine. It looks like a bug may have been introduced between those two versions. The form behavior should be the same when a value in a choice field is selected, whether the field choices display as a dropdown or as radio buttons.
I did a quick test on another site and the radio buttons worked without a problem using version 220.127.116.11. I was helping Karen Flaxer, so am not able to test it again in her site right now, but its good to know that it is working. If I get a chance, I will try to see if I can recreate the issue in her site and report as much information as I can to you.