re: Biscuit help

Kind of hard to tell somebody how to do something without showing them but I’ll try to add whatever hints I can.
I don’t think adding any fence should be necessary.
I hold mine down flat right on the plate. (see pic)

(some people may not be comfortable holding it like that, but I find it works that way the best for me.) Then make sure you push it in nice and straight without lifting it up or down.
Having your wood clamped down solid will also help.
Just practice, practice, practice