Architect, structural engineer. Attended the H.B.S. in The Hague and studied at the Technische Hogeschool in Delft, where he graduated as an architectural engineer in 1922. Due to his love of architecture, he spent some time working in various architectural offices, where he acquired extensive professional knowledge. During his time as an assistant at the T.H.S. Delft (1927-1930), he settled as an independent architect in The Hague. There he was appointed teacher at the Academy of Architecture in 1929, a position he would hold until 1935. All over the Netherlands residential houses, villas, country houses, office, store and other buildings designed by R. de M. were built. Moreover, he brought about numerous renovations. Especially in Eindhoven, Zaltbommel, Nunspeet and Zaandam, there are many buildings designed by him. For his work and studies, R. de M. spent considerable time in Milan. Portraiture enjoyed his interest. He was himself skilled amateur portrait painter and draughtsman.