In the reference manual,
“In high-frequency, low-power mode, the oscillator uses a gain control loop to minimize power consumption. As the oscillation amplitude increases, the amplifier current is reduced. This continues until a desired amplitude is achieved at steady-state. In this mode, no external resistor should be used.”
So RF is internal and the AGC replaces RS. Can Cx, Cy be implemented via the switchable internal capacitors (2,4,8,16pF controlled by bits SC[2,4,8,16]P)?
I am dealing with a design intended to go to commodity volumes: my salary is worth less than a couple of capacitors! If I can remove them from the circuit, I've paid for myself.