My question is too simple apparently (I don't find anyone else asking it).
I want to add the names of the streams/rivers to my maps, but the
annotation option is grayed out unless I prepare a "dummy plat" and
apply it to the map.
Well, I don't have a plat for every single stream on the map! I just
want to identify the streams by name on the map. Later, I will place
some plats on some of the streams. Is it possible to annotate maps with
the stream names?