You need to place the Should Stop somewhere right before the next item will be processed. Typically, you will loop though some items in your process, so the Should Stop goes at the start inside the loop and it will finish the current item but not process the next item if the “Stop” is triggered in Orchestrator.
If your Process is using a Flowchart, then you can just check the boolean from the ShouldStop in a Decision and exit easily. If you are using a Sequence, then you will need an If activity with a Throw activity to exit the ForEach.
EDIT: If you are using States, then set a condition transition to End, so it doesn’t go to Process state for next item
I disagree with this. ShouldStop is important regardless of your project design. For example, Kill (like you mentioned) will halt the process and not continue. This can leave applications and files open. The main purpose of ShouldStop is that you can perform other actions before it stops, so you can complete the current item being processed and clean up the environment. Additionally, for scheduled jobs, you can set a timeout so a job can end after so many hours (you can use Stop or Kill for this, preferably Stop). Another thing to consider to code along with this, is to Log that it was manually stopped and Throw the last received exception that hit max retries so it doesn’t show Green successful, which is something that the REF does poorly in my opinion.