<p>For dartmouth, I'm writing my friend a peer rec...in the case that it actually turns out alright, would it be frowned upon for me to send it to schools like Princeton as a supplemental rec? Or are supplemental recs usually from coaches, summer instructors, etc?</p>
<p>Dartmouth is one of those colleges with the "Peer recommendation" letter. Peer mean that it comes from a person who knows you well and is in your age group.</p>
<p>That in mind a "Supplemental recommendation" would be better from someone like a coach, employer (boss), minister, rabbi, important person...etc, all having the common attribute in that they know you well and can speak about you.</p>
<p>I suppose that a person (as a peer) your age could also write a good supplemental recommendation too, but I would first check out the others.</p>