Can someone help me with scent detection training for my pup?

I say pup, but he's actually almost a year old. We've been working on finding antler sheds from deer because I am a big hunter. He is doing great and he is finding sheds fairly well but I want to teach him to sit next to the antler shed and/or bark at least once when he finds one. This is where I am having the problems. When he finds it he just wants to sit there and sniff, which is great, except when I am far behind him. Any suggestions on how to get him to do this when he finds one?