How to properly configure PFC ?

I have CRS510-8XS-2XQ-IN running latest version - 7.18.2

I would like to configure PFC with traffic class 3 on 2 switch ports.

I created traffic class 3 rule in Switch → Priority Flow Control and assigned it in PFC field for 2 ports in question.

What’s not clear for me is what should I be putting in “Egress Rate Queue3” for both of these ports ?

Is it a link speed ? There is little to no documentation on this.
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Ok I read
https://help.mikrotik.com/docs/spaces/ROS/pages/189497483/Quality+of+Service#QualityofService-RDMAoverConvergedEthernet(RoCE)

it is more or less clear now