Raw is definitely best. They can be fed with or without the shell. Start with just a few because sudden changes in a rabbit's diet of any sort can cause problems. They are a rich food, high in protein and healthy fats, so I would not feed more than a tablespoon per day. Usually people feed them in fall, when the pumpkins are ripe, over a period of weeks. If you are buying the seeds, you could feed them daily for a couple of weeks. They are also good as a rich winter supplement in cold weather, much like black oil sunflower seeds.