Doesn't uncooked rice expand in their stomachs? I think that's why they stopped throwing rice at weddings, because the birds were getting it and it was causing problems. But I don't really know.
Cook the rice first. Even feed it warm if it is cold out where you are. Oatmeal with scratch in it is a great treat too. You can also add black oil sunflower seeds.
I always thought it was probably minute rice that hurt the birds. I don't see how regular rice would differ from any other grain. I do soak rice before i feed it just in case.
On the other hand, I don't know if feeding your chickens just rice and scraps will mean they get all the nutrition they need. Best to go for a balanced diet, I think.