Adding text collection via SDK

Hi Guys,

I have created new facet on account and requirement is to add 3 fields in that facet. Out of 3 fields first should be the check box and rest 2 will be the text fields which have the possibility to add multiple lines.

Unfortunately we cannot use the key user tool to add these fields as it only allows to add a text field which contains a single line or a formatted text field.

Therefore we will need to add these fields via an SDK solution.

Could you please advice on what needs to be done to add a textcollection via SDK for these two fields?

Regards

Nitin