I am going to assume you mean exactly what you said (which seems very strange to me). Do it like this in props.conf :
[source::/nyx/nogscore/log/nogscore-*]
SEDCMD-add_extra_newline_at_end_of_line_after_transactionid = s/(transactionid=.*$)/\1\n/g
Note: After making changes to props.conf and deploying to Indexers (or Heavy Forwarders), restart all Splunk Enterprise instances to enable the configuration changes. This applies ONLY TO EVENTS THAT ARE INDEXED POST-RESTART.
http://docs.splunk.com/Documentation/Splunk/6.2.0/Data/Anonymizedatausingconfigurationfiles
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