Reviving this thread to share a story from the Vibram.
I got to see firsthand how pros call violations.
On hole 8, Nikko was lining up a tough ~50' uphill putt for birdie. Garret Gurthie and Nate Doss were well behind him observing. GG noticed something, went to Nate and pointed. Couldn't hear what was said, but as soon as Nikko released, Nate announced very matter-of-factly, "Foot fault." He called it well before the disc buried itself in the chains for a nice birdie. GG seconded and they explained that by performing a jump putt off his toes, his stance was actually beside his lie rather than behind it.
So Nikko retrieved his putter, adjusted his stance and missed the second attempt. Leading to a brief disc stomping tantrum.