Do I need to feed my free range chickens store-bought feed?

I would get a bag of layena or something and have some feed available for them, free of choice. It has everything in it that they need. Mine go for the feed as soon as they wake up. Then they walkaway from it and free range and pick around the yard till about 3.30 when they go for a final round of feed before they put themselves to bed around 5 pm.
I used to only feed kitchen scraps too, but didnt get much eggs.
As soon as I made the feed available my egg production went up and they looked 'perkier'. They still eat weeds and kitchen scraps once in a while. (spagetti)

 

It's a good idea to have a commercial feed available to the birds to fill in the gaps in what they can find. Depending on your area and environment, they may eat very little of the feed, or they may eat a bit. If you have all hens of laying age, a layer feed is okay to feed. If you have younger birds or roosters, I prefer to avoid the extra calcium in the layer feed and just give everyone an all-in-one type feed and oyster shell or egg shells on the side.

Your birds would probably live okay on just scraps and range, but production may be compromised. Today's birds that are bred for an egg a day for days on end have higher nutritional needs than Grandma's birds did.

 

Couldn't have said it better myself. My layer/turkey flock is free range, but I have feeders available with Purina Flock Raiser available for them in their coops, and oyster shell in bowls for the layers. Even after free ranging all day, they are still hungry and tuck into that stuff with vigor. I also offer a scoop full of scratch grains to the free rangers every day. It's not a complete feed, but it works well as a supplement and they enjoy eating it. Without the complete feed available, birds would probably survive, but take much longer to mature/gain weight and lay fewer eggs.