In order to add any custom fields to the PDF/Print document, please follow the next steps:
1. Go to the plugin settings page;
2. Switch to the "Custom Fields" tab;
3. Choose the necessary post type section;
4. Find and click "[ ]Add Custom Fields" button in the TinyMCE Editor (Visual mode);
5. If you would like to show service custom fields check "Show service fields" checkbox in the popup window;
6. Choose the necessary custom field and click "Insert" button;
7. Shortcode will appear in the WP Editor field. = TinyMCE Editor;
8. Click "Save Changes" button and check the result.
Please note that in order to select the appropriate custom field you need to have it added earlier to the relevant post type while editing it.