RK

RK may refer to:

Science and technology

 * Radial keratotomy, a surgical procedure on the eye
 * Rhodopsin kinase, an enzyme
 * r/K selection theory, in biology, relating to the trade-off between quantity and quality of offspring
 * Runge–Kutta methods, in numerical analysis

Airlines

 * Royal Khmer Airlines (former IATA code: RK), ceased operations 2007
 * R Airlines (former IATA code: RK), ceased operations 2018
 * Ryanair UK (IATA code: RK), UK based subsidiary airline of Ryanair

Other uses

 * Raising Kaine, a defunct Virginia political blog
 * Reichskommissariat, a historical Nazi territorial division