WASHINGTON, Sept 17 (Reuters) - President Barack Obama said on Saturday that Americans need to be ready to "pay their fair share" to narrow the U.S. deficit, previewing his proposals to Congress that are expected to include more taxes on the rich. In his weekly radio and video address, the Democrat said his $447 billion jobs plan that features tax breaks for workers and small businesses, plus funds for public works projects and schools, "will not add to the deficit. It will be paid for." "On Monday, I'll lay out my plan for how we'll do that -- how we'll...