There is a death in the British Columbia Canada death record set in the 1970s for a man named Wall Rivers who was born in Setskogen, Norway in the 1890s. https://familysearch.org/ark:/61903/1:1:FLBX-B8L
His name at birth is Ragnvald #5: SAO, Høland prestekontor Kirkebøker, F/Fc/L0001: Ministerialbok nr. III 1, 1880-1897, s. 28 Brukslenke for sidevisning: https://media.digitalarkivet.no/kb20060719030031
The things to like about Toralf is that his name could be reasonably shortened to Ralph and his birthdate is on the money. But many elements in the family story don't match the records on him, not clear where the Sorenson comes in nor Rivers and the story of leaving at age 13 or thereabouts. But I think I'll check the death record to see if he disappeared or is thought to have drowned or some such.
Cause of death looks to me like appendicitis, so no mysterious disappearance or drowning. Back to drawing board.
Initially the practice is, if the connection is not obvious, is to examine all sorts of "possibles". The conclusion is none of these folks linked to in this post above are related to you. So the search goes on and then Anton noted that there were only 2 Rolf Sorenson with a slightly expanded birthyear (beyond 1889-1891) in the Norwegian 1900 census and so we looked for information about them which might determine whether or not Ralph Rivers could be either. The conclusion of the contributors here was that Rolf Brynjulf Finn Sorenson b 1888 is your Ralph Rivers.
Most of the other posts were about siblings of Rolf, about Rolf's parents, grandparents and Rolf's aunts, uncles & cousins. Which person specifically are you curious / confused about?