For foods to have a kosher certificate, each and every additive used in the preparation of the food should be kosher as well. However, it is not only the food products that matter here, but also the way of preparation of these products.
The additives and the food processing has to be checked by the Kosher auditor before you get the certification.
If you want to get certified, you need to apply for it properly. Therefore, get in touch with Registrationwala to get the certification.