Parametric Vector Field Script + Sample File
The script goes through the surface and evaluates the curvature on each division point, then creates a curve relative to the normal vector on each point of the surface. Curvature values at each evaluation point is considered in order to give length to the curves. The final lines in the function add a circle and extrude it on the curve normal to the surface and scaled according to the amount of curvature. Enjoy!