The 24-year-old, who is available to play in the FA Cup, will remain at Sixfields until January 3.
"With the loan window closing I felt we needed another striker to see us through the next month or so," said Northampton boss Ian Sampson.
"December is a busy time and we need more options up front, and Ryan is a player who I think can help us.
"I think Ryan can come here and do a good job. He is a player with a very good engine and works hard for the team. He has played all of his football at a decent level and has a good amount of experience.
"He will be a good foil for the other players we have here and I am pleased to welcome him to the club."
Source: PA
Source: PA