I had the fairing, front fender, side covers and gas tank painted in a two tone paint scheme, code 130, used on the RS bikes; the colors are Dunkel Blue and Hell Silver. In this scheme, the seat cowl is painted Dunkel Blue but I chose to use Hell Silver instead. And in tribute to the first year 1977 RS, I had matte clear coat applied instead of gloss and a single white pin stripe applied.
This shows how I do the work and a short video showing some of the assembly details.
VIDEO: 1983 BMW R100RS Install Seat Cowl and Seat
Here are the parts.
I installed a combination grab rail/parcel rack.
The hinges on the later seats are designed to slide over the hinge pins and the seat is secured on the rear pin with a clip.