Lost cat appeared

Every summer it seems we get a new cat show up here, hungry, etc. This one is a very loving cat,as soon as the door is open the cat comes in, jumps up on our laps and just wants attention. It is an old cat, a Siamese, looks like a sealpoint, might have some mix, but is very loving, as I said, old, and a bag of bones. Eats everything in sight, including the dog's food when Candy isn't looking. I don't know what it takes to fill the cat up, can't just keep feeding it. My 2 cats don't mind it being around at all. I do want to find the owner. Sometimes folks take their animals with them on camping trips, (we live in a very rural area, lots of lakes etc.) But cats???? I can see dogs. How do we find the owner in that case? The cat came and got some food, then we didn't see it for a couple of weeks. Then here it comes again. This has gone on for over a month. But this time it seems to want to stay. The cat is old, a bag of bones. Ravenous. What is the best food to give it in this case?

A lot of the cats that show up have obviously been dumped off by city folks thinking the farms need "barn cats". Can't believe what I call them in my mind. Usually they are pregnant, and show up in a week or 2 with a litter of babes. Those we take to the "no kill" Pet Rescue. Some are ferals. You really don't know what we get out here in the "farmland".

Any suggestions on what to do, what to get this one to fatten it up some? I really feel sorry for it. It is such a loving cat. Want to find the owner, but. . . . . . .

Jen