The Bulgarian striker, who joined from Manchester United at the end of August, scored a match-winning brace in his first start for the club against West Bromwich Albion on Saturday and Riise is thrilled to have him at the club.
"For Fulham to have a player like him at the club is amazing," he told the club's official website.
"It just proves that we're working hard to push the club forward.
"He came in and scored two goals on his home debut and you can't ask for more than that.
"He's settling in well and all the boys are pleased to have him in the team.
"We'll try and make it as easy for him as possible at his new club."