well, you know that the best way to repair bad boards on lap siding or tounge an groove boards or R-105 siding is to take off the bottom and work up to the bad board then go back down.
some times the bad board is so high up the wall that its not good sense to remove all the lower ones to get to that one bad board.
If that is the case, you can replace the upper board by sawing off that lower piece of the groove so that the new piece will sit right back into the spot. Its just like taking out a middle piece of wood tounge and grooved floor board.
After you pry out the bad board and remove the nails and patch the tar paper that tore, then add your new board as stated, apply plenty of caulk and spackle if necessary, pre drill your holes for the casing nails on the ends and make sure every nail hits a wall stud. Counter sink the casing nails and spackle over and then prime the board and then finish paint.