I have a "witch's chin". What procedure would best give me a more feminine and aesthetically pleasing appearance? (photo)

Your intuition is correct, you need both bone and soft tissue reduction. This can be ideally done from a submental approach where both excessive tissues can be removed.

   You need to have mostly bone and some soft tissue removed to get you the chin you want.This cannot be done simply. You need to have the bone chiseled and the soft tissue carefully removed. there are lots of nerves, both motor and sensory in the way here. If an inexperienced or a non careful surgeon goes in to do this reduction they can be injured. Heck, I have seen nerve injuries with this surgery from high quality surgeons. So much for easy.    Also if the surgery is not done carefully when the muscles heal back down there may be some distorted movement on animation around the mouth leading to a peculiar looking smile or other problems.   I agree you have a noticeable aesthetic problem with your chin and I also agree undergoing a good surgical solution is an excellent idea and should get you the chin you want.   But please see either an excellent General Plastic, Facial Plastic, or Craniofacial surgeon with experience in this work so as to increase your chances of success and decrease your chances of complications.This is skilled and somewhat difficult surgical work. I would definitely approach this surgery from under the chin by a submental incision and not from inside the mouth.