Sketcher > Dimensioning Sketcher Geometry > Working with Dimension Tools > Normal Dimensions > Dimensioning Splines > About Dimensioning a Spline
  
About Dimensioning a Spline
You can add dimensions to a spline by using its endpoints or interpolation points. To dimension a spline, you must dimension its endpoints. You need not add spline dimensions if the spline is attached to other geometry and the endpoints are dimensioned.
You can dimension spline endpoints using linear dimensions, tangency (angular) dimensions, and radius-of-curvature dimensions.