I’ve downloaded the F# plugin from package control github.com/hoest/sublimetext-fsharp but I still can’t use the comment toggle action to comment lines. This has happened before in other languages, how can I teach SublimeText how to comment F#? Thanks!

Create a file fsharp.tmPreferences in your user package directory (ctrl+shift+p -> browse package -> directory user) and paste the following:

[code]

<?xml version="1.0" encoding="UTF-8"?> scope source.fsharp settings shellVariables name TM_COMMENT_START value // name TM_COMMENT_START_2 value (* name TM_COMMENT_END_2 value *) [/code]

Not tested so you might have to adapt it, but this is the idea.
If this work, it could be a good idea to propose a patch to creator of the package to share with other F# user