Turpeinen is quite a common name and found in several places. Fortunately Raatikka is more uncommon and I was able to find Brita Karolina Raatikka in Tervola. She was born on Dec 31, 1875 and married Esaias Turpeinen on December 16, 1894. Brita Karolina is on this communion book page: http://www.sukuhistoria.fi/sshy/kirjat/Kirkonkirjat/tervola/...
They had two children in Finland, Emil Edvard who was born in 1895 but died already in June 1896 and Eino Ilmari, born in April 1896. The Ellis Island record also shows the son as Ilmari (age 3 months).
Esaias was born on August 16, 1866 in Pihtipudas. Could this be your Isaac - although the birth date does not match? The name Isaac might be a variation of Esa?
This census record shows that this family indeed lived in South Dakota: https://familysearch.org/pal:/MM9.1.1/MMRH-6JF
hope this helps