From SK's web page:
Earning points with Icelandair:

You earn Extra points on Icelandair flights between Copenhagen/Oslo/Stockholm and Reykjavik. You also earn Extra points on flights between Reykjavik and Boston, Minneapolis, Orlando and Washington.

You earn 2,800 points in Business Class and 1,400 points in Economy Class per one-way trip between Scandinavia and Reykjavik.

For flights between Reykjavik and Boston, Minneapolis, Orlando and Washington you earn between 5,000 - 7,200 points in Business Class and 2,500 - 3,600 in Tourist Class.