I know that its important to have the LOR on letterhead, but if the LOR is from a DO (who runs their own clinic), is a letterhead absolutely required? How would the DO write one for themselves? Also, are the signatures required as well, given that I've requested their letters through Interfolio? Would it be possible for them to sign it on paper and just scan it to Interfolio, or would there be some easier way? Thanks for the help, I'm just a little confused!