First, there is no "K2 file" that needs to be included really. What you need is to know the item ID of the K2 item that you want to get the extra fields from, then create a SQL query that gets the extra field data from that item. A simple function within your component is all that is needed. Pass the item ID to the function to pull the data.
The hard part is going to be figuring out which item to pull the data from. Somewhere in the process you have to associate the K2 items to each record in your component.