Where do you connect the thin bottom hose from the coolant reservoir on a 1992 Mercury Capri not the one that connects to the top of the radiator?

Actually, this is an overflow hose. The hose shouldn't connect to anything. When the radiator warms up the fluid level in the reservoir tank may rise. If it gets too high, then the coolant will pour out of this overflow hose. If this is happening too often, you may have a blockage in your radiator.