The 31-year-old striker hasn't made the squad for the last two league games after being an unused substitute in the 1-1 draw against Arsenal.
Rosenberg slipped down the pecking order after the signings of Nicolas Anelka and Matej Vydra in the summer then the subsequent arrival of Victor Anichebe and Stephane Sessegnon on deadline day.
The collapse of Shane Long's move to Hull and the stunning emergence of Saido Berahino has pushed the Swede even more to the margins.
Now he claims he is looking to leave The Hawthorns when the window opens on January 1.
"It's been difficult – I'm 31 years old and have barely played in a year and a half," said Rosenberg, who has played just 90 minutes in the Premier League this season across four games.
"I'm waiting for the window in January and see what opportunities are out there.
"I haven't talked to any clubs but I want to play football. I've been patient, but now it's getting too much."
Asked if he has discussed the matter with head coach Steve Clarke, he said: "Not so much directly – more that I'll get the chance but I'm not allowed.
"We have a big squad and he often chooses other players. He signed many strikers before the transfer window deadline so that's made it difficult for me.
"I played and scored in pre-season and feel I could do more. We've played with two strikers this season but the strikers have still struggled to score."
In the interview in his native Sweden, Rosenberg was asked if there was interest from his boyhood club Malmo.
"It's hard to know, I haven't talked to clubs yet," he said. "The dream had been to complete the circle where it all began but it's all about timing."