I wasn't sure if Karo was a brand name of corn syrup, but I ended up using corn syrup (mostly a light vanilla corn syrup I had, but I ran out so I also used a generous squirt of dark corn syrup). I think the recipe came out pretty tasty, but I probably could have gotten away with adding an extra cup of cereal.
PEANUT BUTTER RICE KRISPY TREATS
1 c. granulated sugar
1 c. white Karo syrup
1 c. smooth peanut butter
5-6 c. Rice Krispies
Heat sugar and Karo until hot. Add peanut butter and boil 1 minute. Remove from stove and add Rice Krispies. Mix well and spread into a well greased 9x13 inch pan. Cool and cut into bars.
Oh, does anyone have any pointers for getting hardened cornsyrup-peanutbutter goo out of my glass mixing bowl?