If you are permitted to use a generative Artificial Intelligence (AI) tool like ChatGPT for information included in your work, you should insert an in-text citation and add it to your reference list.
In-text citation:
(OpenAI 2023) or OpenAI (2023)
Reference list
OpenAI. 2023. ChatGPT (Mar 14 version) [Large language model]. https://chat.openai.com/chat