I'm running Airfoil 4.8.3 with Indigo 4.0.10 on Mavericks. While it seemed to be connected, I couldn't create a device with Airfoil. After several unsuccessful attempts, I gave up and started doing something with the iTunes plugin. Then when creating an iTunes scheduled event, I noticed "Airfoil Actions" showed up in the iTunes action list.
Strange?!
But it worked.