This is possible. The list only shows the carriers that are supported by the marketplace. When you're missing a carrier in this list, you best contact the marketplace with the request if they can add the carrier to the supported carriers. EffectConnect will import the carriers automatically as soon as the marketplace makes them available in the list of carriers to choose from.
Please keep in mind that the carrier 'TNT' is equal to 'PostNL'. Some channels still use the old name of this carrier.