This question was posted in response to the following article: http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/fl/controls/RadioButton .html
The "more info on styles" links goes to information on Spark skinning. While that's somewhat about styles, it's probably not relevant to fl.controls. Maybe something more like http://www.adobe.com/devnet/flash/quickstart/button_component_as3.html would work?