"When you get to the business end it's difficult," Smith told BBC Scotland. "Any team that comes to Tanandice is going to get an extremely tough game.
"People think that if you're going for a championship, you will stroll to it but in Scotland you don't do that.
"We know that we will have to work hard to earn our championship."
Rangers need five points from their remaining five fixtures to defend the title they won on the final day of last season.
"It doesn't matter where you win it," said Smith. "You've got to win your games. Tonight was always going to be a very tough match. We have other tough games to play, so we'll wait and see how it goes.
"This is the fourth time we are meeting teams - we have to come here (Tannadice) again in the run-in."
"From our point of view it was a hard-fought point," added Smith.
"It was hard work for everyone tonight. Both teams put a great deal into the game.
"Maybe if we'd shown a little bit of extra sharpness in the last third we might just have got there.
"There weren't many opportunities for either side. I felt we started the game very well, first 20 minutes or so - then it was level, with some excellent defending on show.
"Second half, I thought we had the best of it both territorially and in possession, without creating a great deal of clear-cut opportunities."