 In 1904, Rasmussen married Símun's sister, Anna Suffía av Skarði, and he remained Símun's close friend and coworker.Rasmussen also attended the State Teachers School () in Copenhagen, where his main study area was science.Rasmussen's wife, Anna Suffía, served as superintendent after Símun av Skarði and Rasmus Rasmussen founded the Faroese Folk High School () in Klaksvík in 1899.