My teacher suggested moving my thumb inside the frog, but I feel more comfortable (and the bow feels lighter) with my finger on the bottom of the frog (the flat part). He said to ultimately do whichever feels best, just wondering how others do it. He also said I might want to give German a try, so I ordered a cheapo cuz I tried his and it felt really natural. He also said German/French is akin to a Ford/Chevy debate. Go to it boys and girls! I don't know enough to participate, but would love to see it in action!