(Adds details, quote) Nov 20 (Reuters) - Colombian Camilo Villegas, Canadian rookie Mackenzie Hughes, Swede Henrik Norlander and American Blayne Barber will return to complete a playoff for the PGA Tour's RSM Classic in Georgia on Monday as darkness halted play after two extra holes. Five players finished the regulation 72 holes tied on 17-under at Sea Island Resort including Billy Horschel, the 2014 FedExCup champion, who was eliminated after missing a short par putt on the first extra hole of the largest PGA Tour playoff of the year. "I just blocked it," said Horschel, who narrowly missed a birdie putt that would have won the tournament before flubbing the two-foot par putt to remain in the playoff. More...