How to work with F# .fsx files in Rider?

Question

How to create and run an F# .fsx file without creating/opening the whole F# project?

Answer

It is not possible to create an .fsx file without opening any project: Support creating single file templates (c# / f#).

One can create it in any opened project. For this:

1. Open any project in Rider;
2. right-click on a project name, then choose Add | Scratch File;
3. Choose F#;
4. Type a code and then click Run F# script