Einar Hauge father's name

Hello, my great aunt Ingeborg Hauge Petersen (1877-1960) had a child, Einar, born in Bud, Norway and baptized November 16, 1902 according to a baptismal certificate. She lived in Kristiansund at the time but had the child in Bud. We are wondering if we can find the father's name-it is listed as Rasmus with no last name on the baptismal certificate. Einar was later Einar Hauge Petersen, as he took his stepfather's last name. Do you have any suggestions on how I can find the last name of Einar's father? We believe he may have come to the U.S. at some point so may have died here in the U.S. Thanks for any help you can give me! Inez Bergquist