It really depends on what you're wanting these bones for.
Rec bones are not consumed. They are generally too big and too thick for the dog to chew through. For some dogs these can be as large as weight bearing cow bones for others chicken legs are too heavy. There is a risk with rec bones of fracturing teeth if your dog is an aggressive chewer, some dogs however are really great at cleaning and polishing bones without getting overly aggressive about chewing on them. Generally speaking you should avoid cooked bones or bones with sharp edges.
RMBs - raw meaty bones are bones which are fully consumed by the dog usually as part of a diet plan. Raw diets do require some research. They can include raw chicken, pork, and pretty much anything else made of meat. A lot of people I know start with chicken backs, I usually start with necks, or small birds like game hens.