A couple of the F# app templates for Eto.Forms apps appear to have problems:

The MacOS template for F# doesn't include an item to compile the included Program.fs file.
https://github.com/picoe/Eto/blob/develop/src/Eto.Forms.Templates/content/App-FSharp/Separate/EtoApp.1.MacOS/EtoApp.1.MacOS.fsproj

The WPF template for F# contains a C# project, not an F# project:
https://github.com/picoe/Eto/tree/develop/src/Eto.Forms.Templates/content/App-FSharp/Separate/EtoApp.1.Wpf

I looked through the other project templates in the F# folder and didn't see any similar issues.