This is question have already been asked here How Add Custom Meta Fields to Dokan in New Product
But no one answered that question. What I am trying to achieve is following:
Need to display custom field in Dokan Vendor Dashboard, plugin author have answer with this "You have to customize Dokan plugin to add an extra field on the product upload form. Please open dokan-lite/templates/products/new-product.php and in this file, you have to add an extra field. As we do not provide support to customize our plugin for that reason, I am unable to provide more specific instruction :)"
I have created custom field already using Fields Factory Plugin and it's displaying fine in Add Single Product page.
But I am unable to add that field in Dokan Plugin screenshot below for the location.