As you would expect, use: HotkeyPopup hotkey = new HotkeyPopup();hotkey.Show();
to make the hotkey form appear.
Be sure to add the ReceivedHotkeys method that is commented out in the HotKeyPopup.cs to handle received hotkeys.
MistressPlague/WinForms-Global-Hotkeys-With-Hotkey-Selection-Form
A Simple Hotkey Selection Form With Global Hotkey Support For C#
C#