peanut butter for the puppy

As a new puppy owner, I am trying to learn all that I can about what toys to leave for the puppy while I am at work. I just bought a Kong toy, which was recommended, but I'm still trying to figure out what to put in the Kong. Any suggestions? I heard I should put peanut butter in it, but how much peanut butter can the dog handle?

When I put peanut butter in Tobys I only fill it half full cause he can't get all the way in the back. You could also freeze the peanut butter to make it last longer.

http://www.chazhound.com/forums/showthread.php?t=7802

Also:

http://www.kongcompany.com/worlds_best.asp

Go to tips, then to recipes.

How does one know how much peanut butter a dog can eat at once? I'm assuming he'll eat all the peanut butter quickly since he loves it. And the same thing with cheese? If I put a few pieces of cheese in the Kong, he'll probably eat it all at once, right? Is that okay for the dog? Sorry for these basic questions, but I'm a new dog-owner and I don't want my puppy to be sick.

My dog Kiara and I will be taking a 4 hour plane trip next month. I have 2 jumbo-sized kongs that I will be filling. I have been experimenting with different things to fill.

My most recent "invention" is her dog food, soaked in water, then run through the food processor along with some non-soaked milk bones for chunks.
All three of my dogs LOVED it and it took them a bit to get it all out, they were occupied for atleast 45 minutes.

Peanut butter is a bit fattening, that's what I used to fill the kongs up with, but this seems like a better alternative, in my opinion.