Hi,
If you have a species rugosa rose(Sitka rose is a rugosa rose), then you can plant the seeds in the fall once the hips are ripe. They need a winter chill or they will not germinate. Do not dry out the seeds. Take fresh red ripe hips, remove the seeds, and plant immediately. The winter sowing method(see the Winter Sowing Forum) works great with rose seeds.
If you have a double rose form of a rugosa, then you are best to take cuttings and root them.
Remy