If you want to read records from prpc and publish them to Kafka in JSON format, you do not need to create a custom serialization integration because JSON is used by default. Simply use a Kafka data set to write to your Kafka topic.
If you want to integrate your external Kafka with prpc, and your topic uses a custom schema (for example avro), you will need to deserialize your custom schema and convert to ClipboardPages.
We can give more specific advice if you can explain your scenario in more detail. Also please let us know if you have specific questions about the PDN article, so we can improve it.