I use Reptomin all the time with my frogs. They come in a variety of sizes and are floating.

It takes them a little while to learn to look for floating food if they are used to sinking food - especially if they are in a tank with fish, you have to distract the fish so the frogs can have a chance to eat, or use a turkey baster to squirt the pellets out infront of their face.

I definitely recommend Reptomin though!!!