I would say you should hold off on things like this for awhile. It especially shouldn't be a daily thing, just a reward/bribe. And a small slice to us is a big piece to a rabbit, even a full-grown one.
And it depends how the apple is dried, whether it would be safe at all, at least in my opinion. Companies often use chemicals to speed the drying process. Those products that weren't dried using chemicals say that on their labels, or say they are organic.
I give Honey tiny cubes of dried organic papaya 1/8" maybe. They have more calories than apple, but papaya is good for digestion.