So, first, you need to roll up a newspaper and smack...yourself...for allowing him to take anything from the counter and then encouraging it by playing a game.
You can't allow him to take one thing off the counter and not something else. That's not fair and it's inconsistent. Training a dog successfully is at least 90% consistency.
Since you made a mistake, I would have let him keep the rawhide and learned my lesson rather than chasing him and allowing him to learn the new game. When you took it away, at that point, you just stole it from him. He's not aware that you took it because of the way he got it. From now on, anything of interest should get put away where he can't get it, even if that means on the refrigerator or inside a closet.
That said, luckily the rawhide was not something he wasn't supposed to have. And yes, he needs to learn leave it. Have you done drop it with him? Basically, drop it is leave it except he already has it, so it's trained very similarly.
Leave it is generally trained when you're out and about and he is going for something you don't want him to have. Tell him to leave it and wave a treat in front of his face. When he leaves it for the treat, give him the treat and praise him big-time. It took a trip to the beach for me to teach this to Linus. Every shell, rock, hunk of seaweed, cigarette butt, driftwood, crab, dead bird, etc. went into his mouth and I swear I went through a lb of treats! Eventually, when I said leave it he'd come running and get a treat. Easy.
For drop it, when your dog has something of value like a toy, ask him to drop it into your hand, give him a really great treat, then give it back to him. Rinse and repeat -- make it a game. This is a case in which you might want to break out hot dogs or cheese because drop it can be life-saving and it's important that what you have is worth him letting go of whatever he has. He'll learn not only that when he drops it he gets a treat but that he may even get his thing back, so he will not feel threatened, and he's less likely to get snarky. This I generally train not when the dog is being crazy, but when they are quietly playing with something on their bed. You want to set him up for success. After he is dropping the toy successfully you can do the same thing with chew toys then bones. Just work your way up slowly. And, when he has something he's not supposed to have and you say drop it, make sure that when he does drop it you DO NOT scold him for having it in the first place because at that point you are scolding him for dropping it. If you dog has something he should not have, it means you need to put it away. My throw pillows are still in the hall closet...
Both of these things may be a little more challenging for you with an eight month old that you have played the keep-away game with. I usually teach this pretty much on day one and they've got it down by four months. If you are consistent and make it a fun game, it should be not only fun for both of you, but successful.