Bees will often swarm when out of room, and adding a super may alleiviate some of that (congestion), but ultimately, if they didn't draw any of the foundation out, it probably didn't do a whole lot. if they are not drawing foundation and not bringing in pollen/nectar, then you probably don't need it, they just have more room to defend. But make sure that you are ready with it when they are bringing in more stores.
Actually, you can theoretically split your hive into a lot of small hives right in the spring. You have a bigger issue with Small Hive Beetle (shb) so that may not be as much of an option, but the florida beeks can comment more on that. The small hives can take the most advantage of the best nectar flows to build up. You can probably split again in the fall if your winters are warm enough.
Read read read...you are just scratching the surface....Typically, you end up with about 10x as many hives as you wanted originally :-D (just so you know what happens)http://bushfarms.com/bees.htm