Program.cs

using System;
using Qml.Net;
using Qml.Net.Runtimes;

namespace QmlNetTesting
{
    public class CSharp
    {
        public static void TestMethod()
        {
            Console.WriteLine("Called C#");
        }
    }
    
    class Program
    {
        static int Main(string[] args)
        {
            RuntimeManager.DiscoverOrDownloadSuitableQtRuntime();

            var app = new QGuiApplication(args);
            var engine = new QQmlApplicationEngine();
            Qml.Net.Qml.RegisterType<CSharp>("customtype");
            engine.Load("QML/Main.qml");
            return app.Exec();
        }
    }
}