Traditionally, tuning RF oscillator circuits has been a function of an adjustable capacitor. But capacitance is only part of the circuit, with inductance being the other important portion.

Connecting the feedback capacitors C1 and C2 to pins 3 (FDBK) and 4 (VTUNE) transforms the internal transistor into a Colpitts oscillator. A resonator is also needed; here this consists of C4 and L1, ...