The Rígsþula (found here) ends with a crow giving ominous council to Kon(r), son or Jarl, son of Rígr. The crow seems to urge him to fight Dan and Damp (also spelled "Danp"), supposedly Danish kings. On that note, the poem abruptly ends.
However, as suggested by the Skjöldungasaga and the Ynglinga saga, descendants of Rígr married into the ruling families of Denmark, and thus took control.
These are said to be the only tales of Rígr, but I would think that Dan/Danp show up somewhere else, possibly as genuine historical figures, and there might be a mention of Konr, given that his name led to the term konungr, meaning "king".
In any other sources, is a mention of Konr associated with a peaceful transition of power or a violent one, involving battles (as the crow advised)?