Line a baking sheet with parchment paper.
In a medium mixing bowl, combine peanut butter, confectioners’ sugar, melted butter, and Rice Krispies. Stir until the mixture is well blended and holds together.
Using a 1-tablespoon scoop, portion out the mixture into balls. (I made 27.) Roll until smooth and place on the prepared baking sheet.
Transfer the baking sheet to the refrigerator and chill for at least 1 hour, or until firm.
When ready, prepare the chocolate coating. In a microwave-safe bowl, add chocolate chips and vegetable oil. Heat in 20-second intervals, stirring after each, until smooth and melted.
Dip each chilled peanut butter ball into the melted chocolate, covering completely. Using a fork, lift out the chocolate-covered peanut butter balls. Use a toothpick or another fork to slide the balls onto the parchment-lined baking sheet.
Refrigerate until the chocolate is set, about 30 minutes.
Store in an airtight container in the refrigerator for up to 2 weeks.