KeyPressTracker.Store(KeyCode, Modifiers);

var lastKeyPress = KeyPressTracker.GetLastKeyPress();

if (lastKeyPress == "Ctrl+R" && currentKeyPress == "Ctrl+M")
{
    // Show Refactor dialog
}

Try this one out. Works me in VS2013.

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
    if ((keyData.ToString() == "S, Control"))
    {
        MessageBox.Show("You have pressed Ctrl + S keys.");
    }
    return base.ProcessCmdKey(ref msg, keyData);
}