It in the app description, it reads that it only works in 32bit Mac. However, OS X Lion and up run on 64bit by default. First check your processor (Intel Core 2 Duo and up). Change to 32bit by restarting your mac and holding the #2 and #3 keys at the startup.
There is a latency issue though. When Im on Skype, people will comment that I sound muffled and it takes like ten seconds for them to receive what I actually said.
iPhone 5S 7.0.2 + iMac OS X 10.7.5
deathwish92 about Headset, v1.1.14