For a pacman frog your main concern is going to be calcium supplementation. I would dust his food about once or twice a week while he's still young - less frequently when he is older. Vitamin/mineral supplements are usually less of a concern for large frogs like this because they have more possibilities for a varied diet. Much of the advice followed by frog enthusiasts originally comes from dart frog enthusiasts - when all you feed your frogs is fruit flies (talking about dart frog keepers here) then you really do need to worry about supplements. However, when your frog can eat many other things that are readily available, it's better to make use of varied foods than rely on powdering the same food item day-in, day-out.