There might be a leak in the water pump, or in the radiator. Maybe even check the radiator hoses for cracks and leaks.
Bad head gasket and/or cracked head.
Could be head gasket!
Yes, antifreeze can leak from a water pump gasket.
Sounds like a blown head gasket
is it just residue from where the gasket is gone?, if not there is a possibility that the head is cracked, was the head checked to make sure it was not warped? and pressure tested?, also you might have an additional problem, radiator blockage,thermostat stuck or if its the k series the dreaded ballbearing problem, each of these could cause the gasket to go again
head gasket at shop rates $300-$500
Thermostat sticking. Replace thermostat and gasket.
It could be that your head gasket is blown.
This is a common problem with Ford engines. A scratch is allowing exhaust gasses to seep past a head gasket and into a water jacket. Replace your engine coolant replaced annually until you are ready to have the heads resurfaced.
Could be timing cover gasket or head gasket.
It depends on if you see the antifreeze leaking or it is just disappearing. If it is just disappearing then a bad head gasket or cracked head may be the problem. The smoking could actually be vaporized antifreeze. If that is the case don't run it until you can get it fixed.
Water pump out, ruptured tank on radiator, or head gasket blown probably in that order.