The KF-1 started as a proposed "high-altitude fighter" designated the K.III.
Powered by an ABC Gnat the K-3 first flew in May 1918, and was delivered to McCook Field the next month.
In 1921 Martin submitted an improved version with a larger engine and wider wings.
The version featured a central float and outriggers.
Aircraft of comparable role, configuration, and era Port Victoria P.V.8 "Kitten"