Tipping the therapist of a private studio?

I am getting a massage from a therapist who shares a private studio with a partner (co-owner). I have always tipped my therapist at spas, but I have heard that in tipping etiquette is not proper to tip the owner. Does this apply in this case as well? I would rather tip and be wrong than not tip and be wrong. Thanks!

It’s the same…10-20%

Massage Techniques : Massage Therapy: Asking for Tips