Hi @auribe,
The standalone openNURBS toolkit does not have the ability to project points onto surface, as this is a curve-surface intersection operation and the standalone toolkit does not include intersection calculations.
That said, if you writing a plug-in using the Rhino C/C++ SDK, then you can project points on to surfaces or Breps using RhinoProjectPointsToBreps. See rhinoSdkUtilities.h for details.
– Dale