Really this goes for any game, but for my current needs, how do I measure my Frames per Second in Skyrim?
If possible I would like to avoid installing any additional software.
Unfortunately, Skyrim does not provide a method for displaying its FPS to the player. The console command
tdt (ToggleDebugText) was expected to work by many players, as it did in previous Bethesda games. It doesn’t work in Skyrim, though, so third-party software really is your only choice in this case.
I’ve used FRAPS successfully with Skyrim, the free version is sufficient for just an FPS readout.
In general, if a game or its engine doesn’t specifically provide an implementation of an FPS readout (usually via some sort of console command or similar), then additional software is your only choice.