How do you set a site exception for RFP on the URLbar?

Documentation is very vague:

user.js:
25:  6. Override Recipes: https://github.com/arkenfox/user.js/issues/1080

771: /* 4501: enable privacy.resistFingerprinting
772: / * [SETUP-WEB] RFP can cause some website breakage: mainly canvas, use a site exception via the urlbar
773: / * RFP also has a few side effects: mainly timezone is UTC0, and websites will prefer light theme

https://github.com/arkenfox/user.js/wiki/3.3-Overrides-%5BTo-RFP-or-Not%5D#-rfp

Searching other issues brings up CTRL+I and enabling canvas? but site is still broken

Site what is not working RFP on is twitch d0t tv. Go into any category and scroll and new channels fail to load

Browser version & OS:
Firefox v116.0.2 on Arch linux

ty

🟥 https://github.com/arkenfox/user.js/wiki/5.2-Troubleshooting

• I have read the troubleshooting guide, done the checks and confirmed this is caused by arkenfox
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