project.json

The .NET CLI docs are usually ok, the f# specifics are

• compilerName
• compileFiles
• use Microsoft.FSharp.Core.netcore as dependency

Use the fsc compiler, bundled with .NET cli:

"compilerName": "fsc",

The F# language require files in order, the project.json provide the compileFiles property

"compileFiles": [
    "A.fs",
    "B.fs",
    "C.fs"
],

The Microsoft.FSharp.Core.netcore package contains the FSharp.Core built for .NETCore

"dependencies": {
    "Microsoft.FSharp.Core.netcore": "1.0.0-alpha-151221",
},

The Microsoft.FSharp.Core.netcore it's in the https://www.myget.org/F/fsharp-daily/ feed, so the Nuget.Config should contain

<add key="fsharp-daily" value="https://www.myget.org/F/fsharp-daily/api/v3/index.json" />