My first prototypes with the chip howled at high frequency (I can't recall the exact frequency, but it was above 40 Mhz) whenever I used a Bournes 3296W multi-turn pot for adjustment of the output voltage. Stuffing in plain SMD resistors for a fixed output voltage and the problem went away.
Nick DeSmith's page about this chip goes further:
https://nick.desmith.net/Electronics/NixiePSU.html
Unlike his recommendation, I did find that a small snubber on the FB pin (a 47pF in series with 4.7k) provided enough HF deemphasis that it became stable with the vertical pot. Flat single turn pots also didn't show this problem. The snubber I got from reading the TPS40210 datasheet from TI, where they expose a compensation pin exactly for this situation.
In fact, I've switched most of my designs over the the TPS chip, because their web software allows for a lot of custom configuration and provides recommended starting values for a variety of output voltages and currents: it will compute the best switching frequency, inductor, and compensation network based on how much ripple you can tolerate, whether you want a shielded inductor, etc.
