YITH WooCommerce Multi Vendor allows you to turn your online shop into a marketplace where vendors can sell and manage their own products and the site admin can get a commission on every sale.
The integration with YITH Cost of Goods allows you to control how to calculate the vendors’ commissions when the product has a cost set and choose whether to include the cost of the product in the commission or not.
To set up this to your own convenience, just make sure both premium plugins are installed and activated, then go to YITH > Multi Vendor > Commissions and you will be able to activate the following options:
YITH Cost of Goods handling: enable this to include the cost of goods in the commission calculations, disable it if you want to calculate the commissions only out of the product profit. Show YITH Cost of Goods Information: enable this option to show whether the commission includes the product cost or not also in the commission details. 
For a further configuration of YITH Multi Vendor plugin, please, refer to the official documentation here.