The boat I bought was equipped with a single-line system: there's a cheek block at the forward and aft ends of the boom, on the starboard side, and a padeye on the aft end on the port side. There's also some turning blocks at the base of the mast, and a "bridge" over the companionway with fairlead/cam cleats. A reefing line is tied to the aft port padeye on the boom, led up through the new clew cringle, down to the block on the starboard aft boom, forward to the block on the starboard forward boom, up through the new tack cringle, down through the turning block at the base of the mast, then aft through one of the fairleads and cam cleats on the bridge.
Reefing invloves easing the halyard, hauling on the reefing line ( and helping it a little to run smoothly by grabbing the bight and pulling it forward,) then cleating it when the new tack and clew are snugged down to the boom - then a couple of reef knots in the two sets of reef cringles mid-sail, harden up on the halyard again, and Bob's your uncle.