How to export subkeys with Gpg4win?

I can’t find any information at all about how to use subkeys with Gpg4win or WinPT. I’m learning some features I haven’t tried before, by creating an experimental key that I’m not going to use. I added a subkey to this key, for signing.

But I can’t find anything about exporting that key. The only thing I can do that even brings up any reference to it is the Key Edit dialog, which only lists the ID and other basic info. How are we supposed to give someone the subkey instead of the primary key?