Select the FTBrowseFiles procedure, and enter the "Extensions" button. You should see something like the following window.
Look for the JAL:FileTuner - Local Extension.
Use the list of files to the right to select the files you want to include for tuning. Skipped files will not be in the list for selecting. Each file you select needs to be defined globally in your app.
You may change the "object name" below, but I strongly advice not to change it.