Hey Stephen,
Hm, I am not entirely sure if I understand you here but adding a custom field to a profile type is pretty simple. You just need to follow my example below:
1. Go to the back end of EasySocial and click on "Profile Types" on the sidebar.
2. Click on the profile type that you would like to customize.
3. Click on the custom fields tab.
4. Drag and drop the textbox custom field into the workflow area,
http://take.ms/oPRfV
5. Click on the textbox to alter it's settings,
http://take.ms/PYhd4
6. Click on the save and you are good to go