if housed in the same cage the hens will chase the rabbits and if you intend to breed them later on the hens could kill the kits... Plus rabbits really shouldn't have access to chicken feed because it has animal proteins in it and rabbits tummies are not designed to digest that...
But many do hang rabbit cages in their chicken coops... that way they are separated enough to where the hens won't harass the bunnies and they still have access to the rabbit poo! chickens love to scratch through it eating dropped pellets and bugs that are in there...
Crimson Rose is totally correct. Chickens will kill and eat any "pinkies" or newborn bunnies, and will probably harass older bunnies. Plus you really don't want your bunnies to be walking in chicken poop. An outdoor run is a great idea, but make sure it has strong wire (not chicken wire) and a large gauge wire bottom to stop them digging out. And don't house bucks and does together.