Typically, at an untowered airport, it's something closer to "{airport_colloquial_name} traffic, {your_aircraft_type} {your_n_number}. {MESSAGE}, {airport_colloquial_name} traffic"

So, "Columbia traffic, Cessna november one two three alfa bravo [N123AB], three mile final, full stop, runway one eight, Columbia traffic"

At a towered airport, you'd say "Columbia tower" instead, and you don't have to repeat it at the end of your message.