I have taken only one leaf cutting and I did use a rooting powder. However, I do not believe it actually helped any as the leaf must first start to bud. Once the bud(s) forms, new leaves start to develope at the budded areas and soon after a small root system forms at each bud.
well, as dormancy is approaching, i decided to take a bunch of cuttings today. i took cuttings of all of my mature vfts. i soaked all of them in superthrive, and dipped half of them in rooting powder. nos, i'll just have to wait and see what happens!