I found some good/not so good reviews for different open heel small fins. Of course, there are more websites with more reviews and types of fins but I hope this will help you a little in your search for the perfect ones.
HotShot:
I loved this fins, I have to use 2mm neoprene socks for a confortable fit but other than that I have no complains. It would be nice if they had a variety of colors available instead of just grey/green.
Oceanic Viper:
~These are almost impossible to beat; do everthing fins. Comfortable, fast, and great for snorkelling and scuba. Fairly compact and light weight for travel. Nearly the ideal snorkel/scuba travel fins. I don’t think I’ve seen anything better.
~Only tested them in the pool but flexible yet powerful, nice turning... great dynamics overall.
TUSA Compact Travel-Exercise-Fitness Open Heel Swim Fin
~I was surprised at how small these fins actually are! I don’t know how well they would work for scuba, but probably are great for pool exercises. I plan to try them in the pool asap. Probably good for snorkel too if you mainly stay on the top of the water. Definately can’t fit a bootie into these, but maybe you could wear them with a neoprene sock to protect your foot. Not recommented if you are looking for a fin specifically for scuba.
Zeagle EZ Travel Open Heel Adjustable Fins:
~Easy to pack, velcro straps allow for a lot of size adjustment. Very stiff
~Zeagle really hit the mark on this one. Comfortable fins that are lightweight, compact, and great for traveling. You can wear them with or without boots. Did not have any problem with the fit, as they seem to adjust to your foot size. My friend wears one size smaller in shoes, and we are both able to comfortably wear the size small. Highly recommend.