This article talks about Jump Desktop for iOS's bluetooth keyboard support.
As of Jump Desktop 5.0 physical keyboard support has vastly improved. In 5.0 the physical keyboard works like a regular computer's keyboard. Shortcuts like Alt+Tab or Alt+Cmd just work, arrow keys work, even the Esc key on the physical keyboard now works! You don't need to use work arounds like prior versions of Jump. All keyboard keys and shortcut combinations work.
Win key: When connecting to a Windows machine the Cmd button on the bluetooth keyboard is mapped to the Win key.
Function keys (F1, F2, etc): Apple Bluetooth keyboards have an additional fn key on the bottom left hand corner of the keyboard. Use the fn button in combination with the top row of the keyboard to send function keys like F1, F2 etc to the remote computer.
In addition to full bluetooth keyboard support, Jump Desktop also adds macros for compact keyboards which may not include some standard keys. The table below lists all the supported macros. Please be sure to enable macro support by opening up Jump and tapping the settings gear on the top left hand corner of the main Jump screen. Then in the Keyboard section make sure the Macros option is turned ON.
As of Jump Desktop 7.1 for iOS, you can now see the entire list of support Macros by pressing and keeping the Cmd key held while you're connected to a computer. It will show you a sheet of all the macros that are available. Here is a screenshot: