...
The radio button is used to allow users to make a selection from a group of choices.
You can find a walkthrough on using Radio Buttons for Rich Display Development linked here: Using Radio Buttons
Field Binding Dialog (Rich UI Only)
...
related field property - This property allows you to create a radio button group by associating the radio buttons with a field from your original application. In order to do this the id of the field must be associated with the button group. (Genie Only)