You should actually install SparkFun's boards package.
Go to file -> preferences and add the following in additional boards manager urls: https://raw.githubusercontent.com/sparkfun/Arduino_Boards/master/IDE_Board_Manager/package_sparkfun_index.json
Next go to tools -> board -> boards manager and find SparkFun AVR boards and install it. After that you will have entries in the boards menu for the SparkFun boards. Select the ProMicro and next you can select the speed version matching your board.