Who pays for the RFQ fee and how is the RFQ fee calculated?

If you create an RFQ and receive asks submitted by the seller, the seller whose ask got accepted will pay for the RFQ fee. Each seller is subject to different fee rates based on their trading volume in the past 30 days.

The RFQ fees have a tiered system based on the trading volume:

[Volume $, RFQ fee rate %]