The F Line is one of seven RapidRide lines operated by King County Metro in King County, Washington. The F Line began service on June 7, 2014, running between the Burien Transit Center and "The Landing" in north Renton. Other major stops and destinations served include Tukwila International Boulevard Link Station, Southcenter Mall, Tukwila Sounder/Amtrak Station, South Renton Park and Ride, Renton Transit Center and the Boeing Renton Factory. Unlike most of the RapidRide lines, the F Line does not offer scheduled service during late-night and early morning hours.

RapidRide is a network of limited-stop bus routes with some bus rapid transit features in King County, Washington, operated by King County Metro. The network consists of seven routes totaling 76 miles (122 km) that carried riders on approximately 64,860 trips on an average weekday in 2016, comprising about 17 percent of King County Metro's total daily ridership.