There are two forms of Ranked Choice Voting: one for electing a single candidate, used for offices like governor, senator, or mayor; and another for electing multiple candidates At Large, which is used to elect city councils and school boards. Since nearly all statewide elections in Montana are single-seat, including all state and federal offices, the emphasis has been on the single-winner form.
Multi-winner RCV is used in legislative elections around the world, and historically, has been used in many cities around the US. In fact, Rep. Kortum chose to introduce the conversation about RCV in the Montana Legislature with a bill that would give local communities the option of choosing RCV for their city and school board elections.
Further Reading:
Cambridge, Massachusetts Elections a Model for America
The Effect of Fair Representation on the 2013 Cambridge, Massachusetts Municipal Election