I've recently been trying to really wrap my head around how feudalism functioned, fundamentally. There are a lot of little details that get left out of the typical discussions, which seem to focus on the nobility and the manor house.
So basically what's in the title, how many people was a knight generally responsible for? And was he directly responsible for all of them, or were there people who he depended on to manage the more basic peasants? How large of a territory would a knight rule over? What would their personal home look like?
A knight might be given a manor which would be a Manor House, village and maybe a couple thousand acres. The wealthier ones would have several manors. The top magnates of the realm would usually have hundreds of manors and a castle or two.
Later subinfeudation (dividing land) became unpopular and so knights would be taken on as retainers. That is to say they wouldn’t get land but be granted an income instead and live in their lords castle.