Please read post #4 in this link on how to worm a chicken. It should help you out.
https://www.backyardchickens.com/threads/worms-in-chicken-poop.1575508/#post-26765905
You can drop it down to 1/4ml if you wish. It's tough to overdose with Valbazen or Safeguard. Then again, you dont want to give them a full bottle! LOL.
We eat the eggs after using Valbazen or Safeguard.
Both products are Benzimidazoles. Benzimidazoles are mostly excreted and only a small amount is absorbed into the bloodstream. There is minute residue in the eggs. If you believe that you or a family member might have a reaction to the residue...
I recommend Valbazen liquid cattle/sheep/goat wormer. The dosage is less than Safeguard wormers. The 500ml bottle will last you longer since you'll have reworm your birds on a regular basis.
Dosage is 1/2ml given orally to each chicken using a syringe without a needle. Repeat again in 10 days...