Detached Signature
The area tab "Produce a detached signature" is for creating a detached signature using your private key which must also be in the Key Store.
Right-click on the users name and left click to insert the Key ID in the Key ID area. Next, click "Get Input File" to locate a file. Now select the output location of the signed file. When the signed file location dialog box pops up it will add "Detached-PGP-Signature.sig" to the file. In my example will be as follows (TestFile.txt-Detached-PGP-Signature.sig).
Now, enter the password for the private key of the user you selected and click "Create Detached Signature" button.
If everything went well you should see a message (Signature file created successfully.)
The test file and the signature file will be located in the directory you selected.
Now, let's take a look inside the signature file. The signature files have the userid and the fingerprint in the comment area. All done.
Now, let's go over to Verify Signature Key Store.