This scale multiplier only affects the CircleDOF DepthBlur feature. This is applied after r.DepthOfField.DepthBlur.ResolutionScale 0: Disable Depth Blu x: Multiply the existing Depth Blur Radius with -x: Override the existing Depth Blur Radius with 1: No adjustments (default)
Usage
r.DepthOfField.DepthBlur.Scale [value]
Set via the console (~) or in DefaultEngine.ini / DefaultGame.ini.