We do not have any documents/examples regarding the WebSocket API and Contex posing. The WebSocket API can send the post message to the following Refinitiv Real-Time target:
Please note that the RCC lets you contribute data to Refinitiv Real-Time System.
I strongly suggest you contact the Refinitiv Contributions Real-Time (previously known as Contex) support team via https://my.refinitiv.com/ website to help you verify if it supports the WebSocket posting (via RTDS) or not.
Please choose the "Refinitiv Contributions Real-Time" product as in the picture below.