Save any changes you have made on the configuration tab and refresh the page.
If you are still not seeing the field, make sure that it is not one of the restricted field types listed here.
I've Added a new opportunity field, but it is not available in the dropdown?
Save any changes you have made on the configuration tab and refresh the page.
If you are still not seeing the field, make sure that it is not one of the restricted field types listed here.