Other than really needing some weight and conditioning, I really don't see anything that is glaringly wrong with her. Her feet need some attention, as well, but I'm likely not pointing anything out that you don't know already...Lol! I don't have any experience with the supplement you've asked about, sorry.
She needs a little weight and topline, She has nice kind eyes and a beutiful face. I can't really crit these as she is resting her hind leg. She seems to havea high wither but I think that's beacuse she has minimal toplie and neck muscling. She also seems to be over at the knee. Nice slopeing pasterns and nice shoulder. Good luck with her.
She toes out on the front. Her right front pastern looks more upright than the left. She has a really high wither and her neck is to scronny for my taists. Need weight and muscle but other than that I think she is cute. :)