An F-type star was a classification of stars.
Orellius Minor was an F-type star and the primary of the Orellius system. In 2370, Alixus attempted to destroy the USS Rio Grande by sending it into Orellius Minor. However, the trajectory was off and the runabout was later sighted in Sector 401 by the Romulan vessel Gasko. (DS9: "Paradise")
Kelis' homeworld was the fourth planet orbiting an F-type star in the Delta Quadrant. (VOY: "Muse")
The surface temperature of an F-type star was approximately 6-7.5 thousand Kelvin, according to the Star Trek Encyclopedia (4th ed., vol. 1, p. 258).