If you know how many people a recipe feeds then divide the quantities to meet the number of people dining. For example, if your recipe calls for 2 cups of chicken broth but feeds 4 people, divide the quantity (2 cups) by number of servings (4).
It really depends on how many people the recipe feeds. If you have 4, divide all measurements by four, if you have 5, divide by 5. Basically, what ever number it feeds, divide that number by the amount the recipe calls for.