Rest API, subfield selection while pushing data


I have a project created and data collection is being done, I want to use the Rest API to send the data to database (have created a rest api for post), while providing the end point in the settings, I want to only push a subset of data collected from the form. There is “Select fields subset” field, but the subset fields are not getting saved.

Is there a way to use Rest API to push subset of fields?