Hi Vince,
I understand the requirement. But such functionality is not available/possible with the plugin. The ability to pull custom field value is designed for very simple usecases.
Anything beyond that would involve complexity for most users like delimiter, formatting, HTML etc., 🙂
Hence I would suggest advanced users write a small shortcode using PHP with full control over the output.
Below are some docs related to that.
Creating a shortcode with parameters:
https://wordpress.stackexchange.com/a/172920/3914
Fetching custom field value:
get_post_meta()
Adding the custom PHP code to your website:
How to Add Custom Code in WordPress with Site-Specific Plugin?
Thanks,
Aakash