The implementation of the requirements for controlling counterfeit parts are greatly dependant on the company involved and the product it produces. In clause 8.1.4 the requirement is just to can a process in place to prevent the use of counterfeit parts. This process can include many things from only buying parts form original equipment manufacturers and approved distributors, to performing tests to validate that the product received is actually the product requested. This all come down to what is required for the product in question, and to some extent the risk of actually getting the wrong parts that can cause a problem in the end products.
For more information see this article on the special aerospace terms in AS9100: https://advisera.com/9100academy/blog/2017/05/01/five-special-aerospace-terms-in-as9100-rev-d/