This is my code for a Pro Micro which is used as a HID Device.
Requirements: HID Project from: https://github.com/NicoHood/HID
B16LReplicaV1.0.zip is a Custom Device. In the Boards.txt you can change the pid, vid and the name of the HID Device. Just extract it and add it to your hardware folder under C:/Users/User/Documents/Arduino. Then restart the IDE. Now you can select the board.
Credits: NicoHood for the awesome HID Project