* Rahm shoots 65 to claim first PGA Tour title * At 22, becomes youngest winner at Torrey Pines * Joins elite group of Spanish champions on PGA Tour (Adds details, quotes) Jan 29 (Reuters) - Spanish rookie Jon Rahm eagled two of the last six holes to clinch his first PGA Tour title by three shots in sensational fashion at the $6.7 million Farmers Insurance Open outside San Diego on Sunday. The 22-year-old, who turned professional just seven months ago, covered his final nine holes in 30 strokes to card a seven-under 65 at Torrey Pines South Course and break clear of a crowded leaderboard. Rahm finished at 13-under 275. More...