Custom Field Type, after field is create not able to find on formula builder

Question

Hi All, 
 
 Just create a field type, everything is working fine but there is an issue when you trying to use the custom field on fomula buiilder, the field does not display there does anyone knows why ? 
 
 Thank you.

Rodrigo Manara · Answer

Hi Rodrigo - Unfortunately custom fields of custom field types will not appear in formula builder. This was filed as an issue in the past: 76462 | Custom type field does not appear in the formula builder. The workaround provided in the issue indicates that this formula would need to be added manually via vardef. 
 Thanks, Shawn