First, download and extract chrome_block_rfid.zip to a known location. Open chrome and type in the following as the web address to access the extensions page:
chrome://extensions/
In the top right there will be a slider that says “Developer mode”. Click on this to enable developer mode.
Once developer mode is enabled, at the top right you will see a button titled “load unpacked extension”. Navigate to the directory where you unzipped chrome_block_rfid. Select 1.0.0, then click select folder.