My dog ate some chicken that fell and it might have had a small bone what should I do to save him if he chokes

Was the chicken bone cooked or raw? If it was cooked, and it was only a small piece of bone, feed him a slice of bread or two to help cushion the stomach lining. If it was raw, I wouldn't worry too much about it, dogs stomachs are designed to digest and with stand some pretty nasty stuff.

When it comes to things like splintering bones, and IF your dog actually is gagging or retching or chocking it's always best to get him to the emergency vet ASAP. You could do more damage trying to help.