Have your child's RAD treated while they are young. Our boys were 12 and 15 before we found an attachment therapist and decided to drive an hour and a half. It has really helped the youngest who is now 14. It made no difference for the 15 yo who is now 17. The younger they are the less settled they are into patterns of behavior. I'm sure you have heard the phrase "He is set in his ways." Everyone can change but we must desire change before it can generally happen. With younger kids it is easier (still difficult with RAD) to pull at those little heart strings so that they want it.
As Bear has grown older our plan has changed from working on attachment to working on preparing him for adulthood. He has a psychologist here in our little town who is now seeing him more in a mentor/life coach type roll.
I keep my distance most of the time as any connection...ANY....results in an unleashing of hurtful words. I remind myself constantly to, as a mom, remember that my roll is changing. Prepare him for life.
I pray for him daily and hope that some day something will happen to cause a light bulb moment for him. It will probably not be while he is at home. In Nebraska legal age is 19 so we do have a couple of years left. Whether that is good or bad I do not know but that is how long we have. We just pray and do our best.
Never, never, never quit.