Even before her sublime goal, Kosola was the liveliest player on the pitch.
The winger, who plays for Swedish club Malmo, came close with a wayward cross early in the first half, before forcing a diving save from Runarsdottir moments later.
Iceland's Antonsdottir, meanwhile, had a game to forget with a reckless challenge on Summanen, having already been on a yellow, costing her side.
Iceland have further cause for concern after their captain and star centre-back Glodis Viggosdottir was forced off with an injury at half-time, after requiring treatment twice.