The 28-year old English forward recently signed with the Red Bulls but is yet to have obtained his US working visa, restricting his eligibility to play Major League Soccer.
Roxburgh says the former Manchester City, Southampton and Charlton Athletic striker will head back to London early in the week to get everything sorted out before the visit of Philadelphia Union next Sunday.
"It's an admin thing. It's a process we think I'll be resolved next week," said Roxburgh.
"At the moment as of yesterday we think he'll be going early next week. We're hopeful he's available for us next weekend.
"That's the way it's looking at the moment. It's just been a slow process. But sometimes these things don't move quickly."