Portugal have struggled to find form since coach Carlos Queiroz took charge last summer and hope to overcome a weak start in 2010 World Cup Group One qualifying by beating Sweden in Porto next month.
"It's a shame we didn't score one or two more goals. It is a problem for me and the players to solve, but the pitch was not in a great state and didn't allow us to pass, control and finish more efficiently," Queiroz said.
Queiroz made six changes to the side that was thrashed 6-2 by Brazil in a friendly in November, but despite creating over 20 chances his team could not score from open play.
Pepe was moved up from his usual central defence role to play in front of Bruno Alves and Rolando, but with the Finns posing little attacking threat the performance of the Portugal front line became the focus of attention.
Portugal had most of the possession in the first half, but failed to break down a well-organised Finnish defence. Ronaldo volleyed just wide and Hugo Almeida went close with a header, but Portugal resorted mainly to shooting from distance.
Finland, who came into the friendly after a 5-1 thrashing by Japan last week, had their first chance on 39 minutes when a powerful Mikael Forsell drive was blocked by keeper Eduardo.
Portugal created more chances in the second-half with debutant Orlando Sa shooting wide from close range and defender Paulo Ferreira forcing substitute keeper Niki Maenpaa into a smart save.
The breakthrough came on 79 minutes with Ronaldo converting a penalty after Sami Hyypia fouled substitute striker Danny.
FIFA World Player of the Year Ronaldo was pleased with the performance and said Portugal "had managed to create many chances against a team which has tall and strong players who stay behind the ball".
"I hope this win signals a turnaround for a great year. I am sure things will improve from now on," he added.
