Why would you want to propose to just a friend?
As someone in love with a friend---it's awesome!
Make sure she feels the same, first, or embarrassment might be in your very near future. I had a friend like that, who suggested that to me, and I shut him down--because frankly, I didn't like him that way.
in person or dont do it..
That is a good question. Over the phone. Just tell her. At least you won't be tempted to do the stupid gimmicky things some guys try when they propose.
There isn't one