Vikings lineman Kevin Williams says he never would have taken a weight-loss supplement two years ago had he known it contained a substance banned by the NFL.Williams and teammate Pat Williams are suing the league over its anti-doping policy, which resulted in positive tests for both of them during training camp in 2008.Kevin Williams testified Tuesday that he was trying to meet a weight target when he took the Starcaps supplement.The two contend the NFL knew Starcaps contained a banned diuretic and had an obligation to tell them.