Neil R

I'd say it will depend on wether you intend on staying on the PSMF diet or wether you intend on putting carbs back in on a more permanent basis.
In the case of the former, then one or two days re-feed will be the best option. However, if you are opting for the later then you need to add the carbs back in much slower, to avoid any potential bodyfat gains.
Sart by removing 20g protein from each meal and replacing it with 20g complex carbs. After 4-5 days do the same again. By this point you should be at about 50g protein & 40g carbs per meal. Then, every 3-4 days just increase you carb intake by 10g per meal until you get to about 70-80g carbs per meal.
Make sure you keep a regular cardio routine in place as well!