Here are the insignia worn by RDA SecOps officers on their shoulders. I've made some extrapolation from the insignia seen on the movie, especially from the ones worn by Capt. Trudy Chacon and Col. Miles Quaritch. Unfortunately, I couldn't get insignia for privates and NCOs in that force...
For now, enjoy this!
[img]http://img717.imageshack.us/img717/651/avatarrdaofficerranksco.jpg[/img]