Although not descended from previous Orcadian earls, Rǫgnvaldr could perhaps be considered related to these Norwegian magnates by right of his paternal grandfather's marriage to Ingibjǫrg, daughter of Hákon Pálsson, Earl of Orkney. If this was indeed the case, William's act of using Rǫgnvaldr in Caithness may have been an example of the king playing one member of the ' against another. The ' were people who possessed a claim to an earldom, in accordance with Norse custom, by right of their descent from previous earls. In fact, William made use of the ' when he had earlier granted Caithness to Haraldr Eiríksson, a grandson of Rǫgnvaldr Kali Kolsson, Earl of Orkney. On the other hand, the fact that Rǫgnvaldr possessed no known blood relationship with the earls could conversely be evidence that he was the first Scottish-backed ruler of Caithness without a personal connection to the Orcadian '. In any event, although it is not impossible that Rǫgnvaldr ruled as Earl of Caithness for a short time, surviving evidence does not record his installation as such, and only demonstrates that he was appointed to administrate the province.