I would suggest to find a type of edible seed of the same size (and shape, if possible) of the capsule, have the capsule coloured of exactly the same colour of the seeds (use a proper colorimeter and food colour), and give the capsules mixed with the seeds after a short period of less abundant feeding than usual. Millet? Alternatively, if you can influence the way the capsule is made, try to have a capsule imitating as closely as possible in size, shape and colour a type of seed you know chicken would like and eat. Maize/Corn?

Place the capsule into a meal worm - or some other available worm or insect that is abundant in your area.  You could also try rolling the capsule into some soft bread.

Some small empty capsule shells are available. You can transfer the contents into the small capsule shells and use oral gavage tools. That way, you ensure the quantity being given.

What medication are you going to administer to the chicken? The dosing should be appropriate taking into consideration the weight and health status of the chick.  There can be interactions with the food (diet) the chicken have.  Some medications don't get full potency since it has to be spaced out with food or can be taken with food. Are thinking of giving this orally or in another route of administration?

First thing is to determine whether is essentially required to be given in capsule dosage form due to some physiocochemical reasons. If so, you the coat the drug with HPMC and mix it with normal diet of chicken, shape the mixture into chicken routine diet granules using some binder and then administer it to the chicken.

In administration of drug dosage forms few issues are to be taken into consideration. Why in capsule form? What is the dose and how many times? the drug is soluble in water? What is the taste? is it bitter or else? is there any interaction or affecting efficacy of drug with food?

In my view the drug powder may be converted into granules and to be coated with sugar or any other tasty material. If efficacy is not affecting with food and drug is not far bitter, then better to give mixed with food or may be dissolved in suitable fluid or water just 3-5 ml and may be poured in mouth. 

Dose administration  of drug or any chemical test item in chicken is very simple comparing with other Lab animals. Test item can be suspended or dissolved in suitable vehicle and put directly in to the esophagus or in the mouth cavity with the help of catheter. Chicken has tendency to gulp whatever you put in the mouth. Only thing you have be cautious  about regurgitation  of dosed material .