It's in the folder for whichever zone you want it to occur in. If it's every zone, you'll have to insert it into each. Be mindful that if you do so, you don't overwrite the ones for zones that already have them. (The Veeshan's Peak entrance in Skyfire requires the use of one [for the new key], and the Nexus spires all operate using them, for example.)

That worked! Thanks!