While Southgate believes the Manchester United striker has plenty of room to improve, he believes Rashford possesses exceptional ability.
"He is a special talent," the England manager said.
"We have to remember that Harry Kane at that age had hardly played anywhere near the matches for Spurs.
"You can even compare it to some of those other top players who have broken through.
"Some of the step-overs and things Ronaldo was doing at that age [were remarkable], but Ronaldo wasn't converting them into the same number of goals.
"So we have got to give Marcus time to develop.
"He has still played a lot of football, although maybe not the continuous starts, and I'm really pleased for him that he leaves here full of confidence."