Generally when you are dropshipping products the customers will shoulder the shipping costs and since the cost may vary depending on your customers location.
Some sellers will offer flat rate shipping which may not play to your advantage at all times since shipping costs will vary. So personally I would not offer this.
Rather it may be best that you add a shipping calculator to your site or store. That way your customers can calculate for the cost of shipping.
Hope this helps, please let us know if we can help you with anything else :)