@MAugustyn It is recommended that one should not create or modify the files at WT_HOME/codebase/rest/ptc/domain. You should be able creating your domain here WT_HOME/codebase/rest/custom/domain. Regardless of where you create your new domain the steps below remain the same.
Configuring a Domain
To configure a domain create the following folder structure along with the required JSON files at the custom configuration path:
<Windchill>/codebase/rest/custom/domain
--<Domain Folder>
----complexType
----entity
----import.json
----import.js
--<Domain JSON File>
you can find a detailed document about custom domain at Windchill REST Services 1.5 User's Guide
Tip: Duplicate an existing <domain XXX folder> and <domain XXX>.json at WT_HOME/codebase/rest/ptc/domain and modify as per your needs.
