No I'm not counting the capacitance twice.?
Rp is a measure of parallel resistance not parallel capacitance. At 400-500MHz, the 10073C will load a circuit in a similar way to the loading caused by a perfect 60R resistor in parallel with about a 7pF perfect capacitor. i.e. just as I drew it on the circuit.
Have you ever measured a x10 scope probe using an analyser??
