Briefly, I used the circuit and equation setup on this thread, and used channel 1 for Vin and 2 for Vout.

I took a bunch of random capacitors from a box, not knowing their values, but estimating them in the uF and nF range.

I used a 9880 ohm resistor as checked with a Fluke 87V, it just happened to be around.

I used sine waves, and began at 1 kHz, using a Instek 1003 DDS function generator.

I first measured the FG output alone as Vin,then loaded with the circuit and the unknown capacitance. Generally, with the resistance used [ effectively impedance] Vin ~= Vout passed fc, but it was a good way to monitor both channels.

Accuracy: 0.5% to 1% compared against capacitance measurement by a Fluke 87V.

Some interesting insights:

Since the Rigol is 8 bit, using 1V led to larger voltage measurement errors than using larger voltages, 5Vp-p minimum was better, I settled on 10Vp-p.

I used the Rigol's automated measurement function to measure Vp-p voltages. I simply spun the frequency down or up until I met the cutoff voltage ~ 7.07V then plugged the frequency into the equation.