Can anyone tell me if there is suppose to be anything under the brake resovouir like a gasket or rubber or is it just suppose to sit on the metal bracket I know the clip is to be there to lock it in place but I took it off for the picture. See pic. Thanks

As far as I am aware, the brake-fluid reservoir just sits in the metal frame/bracket and is held in place solely by the clip that goes across the groove in the neck of the reservoir (outside the bracket).