He joined the Miami Toros of the North American Soccer League in 1976, but returned to England to sign for Southport later that year.
He graduated to the club's first-team squad in the 1974–75 season, making his debut for the Toffees on 11 January 1975 after coming on as a substitute in a 3–0 win over Leicester City in the First Division.
Speaking in 2009, Marshall revealed that a dispute with coaching staff at Goodison Park also contributed to his exit: "In the end, I got a bit disillusioned [at Everton].
"[8][9] The winger went on to record five goals and two assists that year, but was forced to leave Miami at the end of the season when the Toros folded.
Marshall's spell in the US ended on a positive note, as he scored a hat-trick in his final Toros appearance, a 5–4 win over the Boston Minutemen on 15 August 1976.