Fluoride rinse should be used separate from brushing your teeth. When you brush with regular toothpaste, your teeth are already being exposed to fluoride and no extra fluoride is needed at this time from a rinse.
Use the fluoride rinse at another time of day when it is inconvenient to brush. If you brush in the morning, after supper and before bed, use the rinse after lunch or a snack for greatest benefit. You may use the fluoride rinse more than once a day. Fluoride rinse does not necessarily need to be used after you eat. Rinsing more frequently is the most important part, but no more than five times a day.
Rinse vigorously (to dislodge food from between teeth) with 10-15ml for at least 60 seconds. Rinsing longer is better. Spit out the rinse and do not eat or drink anything for at least 30 minutes. Waiting longer is better.
There are many different fluoride mouth rinses available at pharmacies and grocery stores. I recommend a rinse of 0.05% fluoride concentration that is alcohol-free. Buying a higher concentration of rinse is not necessary because frequency of use is the most important point. I would rather you buy a lower concentration of rinse and use it often. Be sure to keep the rinse out of the reach of children.