Please continue to let me know if you talk with Ms. Ryan about RIFNA.
Also, Mrs. Louann Teague sent me this information on another organization.
The USEF High School Athlete program recognizes all disciplines and is supported by the United States Equestrian Federation.  They support lettering in high school grades 9-12, send a work log to the student, and the student does not have to compete in USEF competitions only. 
Check them out at USEF.org

While doing a little research, I also found Intercollegiate Horse Show Association at IHSAINC.com

Ricky Wheeler
Area Animal Science Teacher
Central Region - Agricultural Education
711 Kite Road
Swainsboro, Georgia 30401
478/289-2549 (o)
478/595-5351 (c)