It’s important that a reef pennant heaves the new clew of the mainsail aft as well as pulling it down. If it doesn’t, the foot will have too much curvature and the reefed sail will be too powerful. A flat sail drives well without creating that nasty tendency to heel and gripe that many of us have known. It’s quite common to find that a rigger or builder has sited the lug for the first reefing pennant too far forward on the boom. If so, secure the bitter end of the pennant at the clew fitting itself until you can get it moved. Shift the others back a notch for good measure if need be. It’s not ideal, but it beats the daylights out of the alternative.