Hi,
While editing a payment configuration in the HikaShop backend, you will see this:
You can select the vendor that you want to assign the payment method.
In the screenshot you can see a little warning message, telling that the vendor restriction won't work.
It is because there is no "vendor limitation" set in my configuration
So you have to put a vendor limitation (so only one vendor will be accepted in the cart).
You can also use the second option to only propose the payment method for the current vendor (in "current vendor" I mean the vendor of the products in the cart).
This option is useful only if all of your vendors have a payment method and you don't want to display the generic payment methods.
As you can see in the first screenshot, for each payment method you can select the "mode", if you are in "commission" or in "fee" mode.
It indicate who will receive the money (you or your vendor). And HikaMarket will understand and will process correctly the fees depending the options.
Regards,