The former Werder Bremen striker joined the Baggies yesterday.
Speaking about his decision to sign for the Baggies, Rosenberg said: "I met Dan Ashworth a few weeks ago in Sweden and the head coach in Malmo during the pre-season tour.
"I had a lot of offers but I have never played in the Premier League.
"I have played in a lot of leagues - but not this one - and it was something I really wanted to try.
"Then I met both Dan and the gaffer and they both talked a lot about the system and how they want to use me. I also talked with Jonas Olsson a lot and he had positive things to say about the club.
"It was an easy decision in the end.
"It's a great league for Swedish players as we grow up watching it."