Well i did a search of the surrounding parishes,
I think you will have to learn how to use the Hiski parish search.Once you learn to use it, you can trace your family back.
The Rönn name is quite widespread over Finland.
Let me make a chart up on how to use Hiski and i will send it after Christmas.
If you want to try to learn it here is the link in Finland.Hiski is the one plus the parishes of Finland.IT also has a mailing list that you can join and a seach engine too.http://www.genealogia.fi/indexe.htm