Waitlist Updates: Letter of Rec

So I am currently on 5 waitlists and want to submit an additional letter of rec from one of my professors. Should this letter be submitted via amcas or sent directly to the schools at which I am waitlisted? Also, if it is to be emailed directly should that be done by my professor or by myself?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums