As per Your query, the said transporter is GTA then Yes You will pay GST Tax under rcm basis. If he is not a GTA then no need to pay GST Tax under rcm basis.
As per Notification No. 11/2017-Central Tax (Rate) dated 28th June, 2017, “goods transport agency” or GTA means any person who provides service in relation to transport of goods by road and issues consignment note, by whatever name called.
This means, while others might also hire out vehicles for goods transportation, only those issuing a consignment note are considered as a GTA. Thus, a consignment note is an essential condition to be considered as a GTA.