Program.cs

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Drawing;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Configuration;

namespace F_Key_Sender
{

    internal static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            // -------- This code seems to be needed to actually get it to work with high DPI awareness even after adding app.manifest and app.config stuff --------
            // Also need to add reference to System.Configuration as dependency by right clicking Project > Add > Reference > Search: System.Configuration
            var section = ConfigurationManager.GetSection("System.Windows.Forms.ApplicationConfigurationSection") as NameValueCollection;
            if (section != null)
            {
                section["DpiAwareness"] = "PerMonitorV2";
            }
            //------------------------------------------------------------------------------------------------------------------------------------------------------

            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new MainForm());
        }
    }
}