Keep in mind that one tablespoon of peanut butter contains about 90 kcal, 72% of them from fat. Look at this amount in relation to your dog's daily caloric intake. Logically, a larger dog who eats e.g. 900 kcal per day can have a little more than a small dog who eats maybe 300 kcal per day. The idea is to not feed a significant amount of kcal of the daily allowance in PB, since there are other nutrients that are more important to your dog, and if you feed too many calories per day, your dog becomes overweight.
Also make sure you use peanut butter that doesn't contain salt, sugar, corn syrup, hydrogenated/partially hydrogenated oils etc.
Plain yogurt is best, don't use anything with artificial sweeteners and avoid sugar too if possible. If you think plain is too boring and want to add a bit of flavor, add fresh, pureed fruits.
You can also use apple sauce, pureed fruits and veggies (no grapes, raisins and onions though) to hold the kibble together, or even pureed/ground meat if you want to, but be careful, since bacteria overgrowth occurs rapidly in ground meats.