Welcome Markus!! Really looking forward to see him in the stripes. Gives another very good option for SC. I've seen a fair amount of him from his Ajax days, and he was never a traditional target man, as he was more mobile. As I think Pete is better down the middle, I would think you could use Rosenberg best as a right or left sided forward in a 4-3-3. Obviously depends on the tactics , opposition etc. If you are looking for pure wingplay, he is not that type of forward, so the team might lack some width with him.
But he is good at running with the ball, and getting decent shots in, and I think he will give us a far greater goal threat than Cox or Fortune.