The pilot was on an ILS approach to runway 28 when he reported that he touched down beyond the point at which he intended to land. The pilot was landing with a tailwind. The pilot reported heavy rain at the time and he added power to cushion the landing, which contributed to the location of the touchdown point. The copilot stated that he expected the pilot to do a go around. According to witnesses, the airplane landed at a location with about 2000 to 2800 feet of runway distance remaining. The airplane went off the end of the runway and collided with the localizer transmitter facility and a fence. The landing gear collapsed during the impact sequence. The runway is 6015 feet long and the last 2000 feet downslope at about a 0.85% gradient. According to Lear Jet, the landing distances based on the prevailing conditions, respectively, for a dry and wet runway are about 3350 and 4690 feet.