Hi there, I dont think Kermit looks dangerously skinny but is a little under weight. This could be due to the fact that you have only had him for one week and it can take a new frog a while to settle in. The move can course a lot of stress to a frog and this could be the case for Kermit. The fact that he is eating is a good sign so I would just feed him every day until his weight has improved, then feed him every 2 to 3 days as much as he can eat in 15 minutes. With it being a week he should be starting to settle as long as he has plenty of hiding places to feel safe in his enclosure.

With Whites Tree Frogs, males are 3 inches & females 4 inches when they reach adult hood. If you haven't already the Whites Tree Frog care article would be good to read to check that you have the right temps and set up etc. Kermit is a cutey by the way.

Cristen if his weight does not improve then it maybe something else and I would get him to the vet immediately.