"We really had no option but to win today so to get the three points and control the game as well as we did was very, very pleasing," Smith said.
"We're trying to do things correctly, from how we perform to how we prepare for games, and I think that had a big part to play in today's result.
"We had players out but I thought the young lads who came in did a good job for us. I'm proud of them today and Sam ... what a strike to win a game of football."
Meanwhile, Southern United coach Mike Fridge reflected on an outing from his side that failed to produce enough energy to trouble the visitors.
"We're disappointed with the result," Fridge said. "We never played well in the first half at all.
"The goal was an absolutely fantastic free kick but I'm disappointed in the sloppy way we gave the free kick away that led to the goal.
"We were never in the first half, we seemed a bit sluggish and we didn't close down or press.
"We were a bit better in the second half with maybe half chances if anything, but - at the end of the day, we've got nothing out of it."