First time mother rabbits sometimes are a little confused. They operate on instinct alone the first time and often do things out of sequence or not at all. She will likely do better next time around.
There should be no need to hand-feed the single kit. Instead, take the kit in the nest box to the doe early morning and evening so she can feed it. You'll be able to tell if it has eaten because the belly will look quite rounded afterwards. Mother's milk is far better for the kit than any formula.
Singleton kits often have trouble keeping warm. Make it a nice nest with hay and that fur she is pulling and -- if it is chilly - give it a hot water bottle. A screw-cap bottle filled with hot water with a sock pulled over it works very well. Lay it on one side of the nest box so the kit can cozy up to it or edge away as needed.
:good-luck: