If you're looking to import custom field data with a CSV file, the easiest way to ensure the CSV file is formatted correctly is to set-up a board with your preferred custom fields and export the CSV. 

Note: The CSV Export will include any custom field that has been added to the board, including global custom fields. 

From there you can add and edit the data as needed, then import the CSV file as a new board.

You can also manually add custom fields to our CSV template to import data into Rindle. It's important to note that the custom field name must be formatted properly for the the import to work.

In the header row of the CSV, add the custom field prefixed with cf_ followed by the custom field name, exactly how it appears in your Rindle account.

A custom field named Estimated time in Rindle...

should be formatted like this in the CSV file

cf_Estimate time

Any custom field that has been added to a board, including global custom fields, will be automatically included in the Zip File Export. When imported, the custom fields and all custom field values will import accordingly.