Driven Properties
The Driven Properties section of the RBF Drivers panel is where you define the outputs for the RBF driver. You can add almost any property of any object here.
Note
Just like Blender's native drivers, driven properties need to be integers, booleans or floats. In practice you will probably only ever be driving float properties.
Driven Property Types
Much like Blender's driver variables, you can select from either Single Property or Transform Channel. You can also provide a useful name for the property to help you keep track of things.
Single Property
The Single Property type allows you to set a path to any of Blender's properties (though it will need to be an integer, boolean or float property to be driven). The simplest way to do this is to select the object you want to drive, then copy and paste the path to the property by right-clicking on that property in the user interface and selecting Copy Data Path from the context menu.
If the data path is incorrect, or the property cannot be driven, the path will be highlighted in red.
Transform Channel
Selecting Transform Channel allows you to choose a transform channel to drive. If you select an armature object, you can (optionally) drive a transform channel of a pose bone. If no bone is selected the transform channel on the object itself will be driven.
Note
Transform Channel properties are really just a convenience. Driving the X Location channel of an object is entirely equivalent to creating a Single Property for the "location[0]" path.
Note
Unlike inputs, the rotation modes available for driving rotation channels are limited to Euler, Quaternion and Axis/Angle to match the types of rotation properties available for objects and bones. The rotation mode of the driven property should almost always correspond to the rotatation mode of the object or bone being driven. When you select an object or bone, the correct rotation mode will be set for you automatically.