Mine are both raw fed, and I've introduced oldies unused to the diet onto it without a problem.

The best 'starter' I've found is chicken wings, as advised, and either holding on to the tip and encouraging chewing that way, or bashing them up with a rolling pin first so they can't choke on larger bits of bone if they swallow them. This means that until they learn to chew they won't get the benefit of the bones helping to keep their teeth clean, but better that than a choking risk if they try and swallow a large bit whole.

As for the choking risk, mine have occasionally brought up food, and then eaten it again. The main risk from choking is if your dog is quite food possessive and you feed it quite close to another dog, this goes for any type of food, dogs fed on complete all their lives have been known to choke. Smaller breeds that sometimes posset their food (gulp in large mouthfuls to the back before chewing) are more at risk than larger breeds from the reading I have done.

Good luck with the raw feeding, mine look the picture of health on it.