In a large mixing bowl cream the butter and peanut butter until smooth.
Add the powdered sugar and vanilla, mix well.
Add and mix the rice krispies to the peanut butter mixture.
Refrigerate for 1 hour.
Scoop 1 to 1 1/2 tsp of the peanut butter and form into balls.
Refrigerate of 15 minutes.
Dip peanut butter balls into melted chocolate and place on wax paper.
Chill until ready to serve.