public class SendKey
    {
        const UInt32 WM_KEYDOWN = 0x0100;
        private const UInt32 WM_KEYUP = 0x0101;
        const int VK_F5 = 0x74;

        [DllImport("user32.dll")]
        static extern bool PostMessage(IntPtr hWnd, UInt32 Msg, int wParam, int lParam);

        public static void Send()
        {
            Process[] processes = Process.GetProcessesByName("Oblivion");

            foreach (Process proc in processes)
            {
                PostMessage(proc.MainWindowHandle, WM_KEYDOWN, VK_F5, 0);
                Thread.Sleep(200);
                PostMessage(proc.MainWindowHandle, WM_KEYUP, VK_F5, 0);
            }
        }
    }