Over the years I have racked up some experience with frost bite. My birds are very much out in the elements and with the exception of combs are very resistant to frost bite. Exceptions involving feet almost always involve affect bird being in poor health or underweight. Chickens can be hard to read on those issues without periodically handling them. You can cheat by blocking wind and keeping them warm but birds themselves can still defeat that effort.
Your current bird would be better served if you restore its weight before returning it to the coop. Also for all your bird I suggest you make sure they are getting sufficient grit and have a diet with a little more energy and protein than is typically used for laying hens which can be supplied by mixing in a grower feed into the mix. Providing small amounts of shell corn can be advantageous once protein requirments are met because the corn is enticing enough to stimulate feed intake even after birds are satiated on the complete you are using. The added crop fill will make so more fuel is in the furnace even into the wee hours of the morning. Right after the crop is emptied the birds will tap into fat reserves which pulls weight down and compromises their ability to generate and conserve heat.
Your current bird would be better served if you restore its weight before returning it to the coop. Also for all your bird I suggest you make sure they are getting sufficient grit and have a diet with a little more energy and protein than is typically used for laying hens which can be supplied by mixing in a grower feed into the mix. Providing small amounts of shell corn can be advantageous once protein requirments are met because the corn is enticing enough to stimulate feed intake even after birds are satiated on the complete you are using. The added crop fill will make so more fuel is in the furnace even into the wee hours of the morning. Right after the crop is emptied the birds will tap into fat reserves which pulls weight down and compromises their ability to generate and conserve heat.