I wondered what the recommended doses of black seed or oil are. I came across some studies. This is not medical advice. This is just a set of papers of studies. I take 1 teaspoon of seeds ground into yogurt.
A link with links saying that black seed oil has benefits.
I did the math to convert.
https://c19ns.com/
For 200 pound person. Around 1 teaspoon of seeds per day or around 2 black seed oil capsules per day. This is 40 mg/kg/day of seeds. One capsule is 500 mg oil.
another study used 90 gm (2 fluid ounces) honey for a 200 pound person and 2 teaspoons of black seeds, per day. This is 80 mg/kg/day of seeds. 1 gm honey per kg.
Are you taking this just for COVID benefits? In that case, you’ll have to read each paper and calculate. Or do you want to incorporate this in your daily food in general? If latter, then, some cultures eat as little as a sprinkle or as much as a tbsp, daily. With that info, you can add a spoonful to your food if you want.