The file is officially attached to Knowledgebase technotes such as IN1411 - RSLogix 5000/Studio 5000 Source Protection Tool on the Rockwell Automation Support site.
You generally do not need a third-party download for this file, as it is often already on your system or available through official Rockwell channels: rs5ksrcptc.exe download
You must link to or create a sk.dat file (source key file). This file acts as the "key" to unlock your code later. The file is officially attached to Knowledgebase technotes
You can download the latest tools by searching for "Studio 5000 Tools" on the Rockwell PCDC . How to Use the Source Protection Tool rs5ksrcptc.exe download