It’s pretty straight forward. It’s function 26.
tokenId (put in the token)
receivers:
[‘0xfirstaddress’, ‘0xsecondaddress’]
basisPoints (must not exceed 10000, below is an example of a total of 10%, 2% to first, 8% to second):
[200,800]
You can try it on your goerli contract then use royaltyregistry.xyz to see if it’s what you expected.