Damn. I wrote an answer and I guess I hit the wrong button and it's not here.
That design will fail to operate on a fixed freq when the inductor is large for the freq. You MUST use an RC network with a time constant of over 300nS (but not too much over) on the current sense wire. Otherwise, say you have a large inductor for low ripple and insensitivity to input voltage. You shoot for 1 amp current. The inductor only decays to 990mA at the end of the cycle. The 9910 turns on the gate, say the gate charges with a brief 50mA current pulse- that goes through the gate and the current sense resistor. 9910 senses 1040mA and shuts off instantly, skipping the cycle. Happens next cycle too, even though the inductor's decayed to 980mA. Like 6 cycles later the inductor's at 940mA, gate charge makes a brief 990mA reading, not enough to trip the 9910, so the 9910 gets past that pulse then has a nice long charging cycle for once to put the inductor current back up to 1 amp. Effectively it may be operating at a fraction of the intended freq due to cycle-skipping.
The 9910 has a fixed on-time configuration if the Vout/Vin is more than 0.5 which will be stable.
The output does NOT need a cap.
Isn't that inductor huge for what you want to do? Are you even sure it's not saturating? Larger inductors usually come with lower saturation current and higher resistance unless you go with a physically larger device.