I use a bit less cereal, this makes the treats a little chewier.
3 T margerine
1 pkg 10oz marshmallows (about 40)
5 C Rice Krispys
Melt margerine in a large bowl in microwave. Add marshmallows. Heat 30 seconds at a time stirring each time until mallows are melted and smooth. Add krispys, mix quickly and well. Press into a large sprayed cookie sheet, cool, cut and eat.
Another option would be to use cheerios.