If the Visa card you are talking about is a RMB/USD credit card, because the merchant charges USD, then USD will also be included in your bill. If the equivalent amount of US dollars is returned to the card before the bill expires, no handling fee is required. If you repay in RMB, Visa will charge you a currency conversion fee. (In addition, please note that if RMB is used for automatic repayment of US dollar bills, please ensure that automatic foreign exchange purchase repayment is enabled. )

If you are talking about the RMB/USD Visa dual-currency debit card, since there is only RMB in your account, there is no USD, so you will deduct RMB as a response while swiping the card and directly charge the relevant fees.