Please explain how to fill the WordPress subtitle automatically from Newsomatic.

I am new to the Newsomatic API for WordPress. I can't find a way to prefill the WordPress Subtitle field when Newsomatic creates a post automatically. I see how the title, post, and extract fields can be pre-filled with static information, or variable information, using shortcodes. However, I am not able to find a field on the API's "Main Settings" page or the "Top News to Posts" settings page. Can you please explain how I can fill the WordPress subtitle automatically from Newsomatic? I understand how to work with the title, but I thought there would be a subtitle input field right below the title input field on the "Top News to Posts" settings form. Thanks.