Souter was signed as a developmental player by Kansas City Wizards in May 2008 after impressing head coach Curt Onalfo during a two-day open tryout. He made his debut for them on 13 September 2008, coming on as a second-half substitute for Herculez Gomez against Los Angeles Galaxy. He scored his first Major League Soccer goal against Toronto FC in the 79 minute. Josh Wolff gave him the goal through an assist.
