I use terry cloth towels folded into 1/8ths so I can apply even pressure. The main thing when using DACP or SFP is to work the product until nearly clear and dry. Obviously it is easier to do with a buffer, but you can do it by hand. I wipe off the excess with terry cloth towels.
S100 comes with it's own small foam applicator, but once there is room inside the jar for the larger Meguiars hand foam pads, I use them. I wipe off the excess with microfiber towels.