you learn the restrain potion from a quest you get from Bernard, he asks for help with sexual urges as a quest which then allows you to study the potion at home and learn it after accepting it. doesn't even need to be finished to learn the potion lol. you can also use Ben Dover's guide which has all recipes!
also this is the recipe. if your good with just using a comment!
red berry
nut
empty
nut
red berry