Neither Coertzen nor http://huguenots-france.org/france/refuge/afrique_sud/embarques.htm cite this man's surname as van Vlekkeren, and looking at the manner in which van... is used on the marriage register Source, I would suggest that this is a description of his place of origin, not his surname.
I'd say his name was Roelof Jonasse, not Roelof Jonasse van Vlekkeren.