//Place this in the import section.
import flash.external.ExternalInterface;
//Place this some where in your code where you can access the stage object.
stage.addEventListener(KeyboardEvent.KEY_DOWN, keyHandlerfunction);
private function keyHandlerfunction(e:KeyboardEvent):void
{
if (e.keyCode == 116) {
ExternalInterface.call("window.location.reload()");
}
}