Yeah, I looked at those 1st, but none of them seemed to use those specific tiles. =/
The four roof styles on exterior-C are the same structures, only with different coloring/textures. They are always used in the same way.
The way they're placed in the tileset is not exactly the same way they're used on the map due to space restrictions - the middle row contains the special edges for the roofs to the left and right.
There is a total of 14 tiles for each of the four roofing styles (red, blue, snow, wood)
The sample map "regular town" contains a roof that uses the red-style-tiles on the top left, directly visible when loading it. The other three styles can be arranged in a similiar way, but not all styles get such a building for them in the sample maps.On the same sample map, in the lower left part, there is a smaller house using part of the blue tiles for a similiar roof, and still below that are two houses using the red and blue roof tiles for roofs in a different structure - but the tiles are the same.
Edit:
Forgot to mention that for each of those four roof styles, there is also an autotile roof on A - you need to mix that tile in as well to create all the different options, so it's in reality 15 tiles for each style.