 The RCM were looking for young adventurous men, who were interested in working on a rubber plantation in the South Tapanuli Regency of North Sumatra, Dutch East Indies.In 1920, at the age of 21, Konijn boarded a freight ship and left The Netherlands for Medan, Sumatra, Dutch East Indies.The Tapanuli rubber plantation proved to be an excellent learning experience for Konijn and by September 1927 he had been promoted to the position of Acting Administrator (“administrator” is the then used terminology meaning “manager” of a plantation).