Fillet radius and arc dimension tool
This tool works much like the Bezier curvature dimension tool. First create a circular arc by using the CADtools fillet or arc tools. Select the Fillet Radius Dimension tool and position the cursor directly over the path. Click and drag directly over an arc or fillet to display the radius of the arc or fillet at the cursor location. Click and drag to position the fillet radius dimension. Hold down the option key while dragging to constrain the tool to the center of the radius. Hold down the control key while you are dragging to toggle the placement of the fillet radius dimension text.