Try checking out this link:
https://www.psychologytoday.com/us/therapistsAnother suggestion is to Google something like: therapists and DBT and BPD and the area you live in, and plenty of resources should come up. Also, look at DBT web sites, and contact info if there are no therapist listings to ask if they can recommend someone in your area.
It's great that he's acknowledging it and that you are supporting him in looking for the most appropriate therapy. Good work!
