You did say K100??
The BMW part number is 12 13 1 459 513.
If you are thinking it will replace an R dual O/P coil you may be unable to, though I must admit I've never contemplated it or heard of it being done.
The K coil is indeed a dual O/P coil, 2 being required for the K100 with one feeding 1 and 4 cylinders, the other 2 and 3. They are powered from the computer so are supplied 12v to the primary. The actual resistance of the primary may not be compatible with the ignition control unit of the R.
Bill..........................;-)