He was the son of Ole Rynning, who served as the bailiff (fogd) in Senja and Tromsø, and his wife Golla Hveding.
His interest in such practical matters made him a typical example of a so-called "potato priest" (Norwegian: potetprest).
[2] In Norway, he worked as a Sunday school teacher in Trondheim for a time and as a tutor at the home of Eiler Hagerup Holtermann at the Austrått Manor.
[4] In 1803, Rynning received a prize of 200 riksdaler for his work Tanker over Tangbrændingens Indflydelſe paa Fiſkerierne og Agerdyrkningen (Considerations on the Influence of Kelp Burning on Fishing and Agriculture).
[5] He also received a prize from the Norwegian Society for Development (Selskabet for Norges Vel) for his work Odelsrettens Indflydelſe paa National-Charakteren og Velſtanden i Norge (The Influence of Allodial Rights on the National Charity and Prosperity of Norway, printed in the journal Historisk-philosophiske Samlinger in 1813).