have a custom alert action scripts which have UI. If I give a fieldname in UI that needs to get value from search result and append to sid. How can I use $results.fieldnme$ or any other solution for this.
For Custom Alert Actions tokens you could use this guide:
https://docs.splunk.com/Documentation/Splunk/7.3.0/AdvancedDev/ModAlertsLog#Pass_search_result_value...
https://docs.splunk.com/Documentation/Splunk/7.3.0/Alert/EmailNotificationTokens#Search_metadata_tok...
So in your case if you want to pass some field results (lets name it Results_To_Pass) and also the sid of the search, you could put it like this in the UI:
Results: $results.Results_To_Pass$
Search Job: $job.sid$
Then the python script would parse this and perform its particular function.
If you could provide more info it would be great.
Hope it helps.