Is there some articles show how to convert an existing VCL application to a Remoting SDK Server?
You can add new RO service via File->New->Other->Remoting SDK->Remoting CodeFirst Service Module
.
also you need to drop server component and message to your server datamodule and relink them:
that’s all.
another way is create a new RO SDK server from scratch using VCL standalone (CodeFirst)
template - https://docs.remotingsdk.com/IDEs/Delphi/NewServer/ and then copy server datamodule to your existing project. It can be more preferable because wizard will create server datamodule for you.