i just bag mine,. i do not want to attach one to the handguard or mod the reciver to take one,.. over on The AK forum i think there where one or two guys that put bi pods on there PSL's
Drill and tap the receiver in front of the magazine and put a short section of rail (5 slot) on it. Then use a GG&G. Floats the barrel as much as possible.
Once the adapter is installed on your handguard, attach the Harris bipod of your chosing, but make sure that you don't overtighten either the adapter or the bipod down to avoid cracking the handguard.
Again, this works well as long as you don't go "gorilla" on the install.