April 12 (Reuters) - Futures for Canada's main stock index fell on Monday, weighed by lower gold prices, as investors geared up for the start of the earnings season. Gold prices eased as U.S. Treasury yields remained elevated, denting the appeal of bullion, while investors waited for this week's key U.S. inflation and retail sales data. The Toronto Stock Exchange's S&P/TSX composite index .GSPTSE ended flat at 19,228.03 on Friday.