Here is a tutorial on how verify your site through your Google Merchant account:
1) Go to google.com/merchants, enter your Google Account settings and sign in.
2) a. Go to General.
b. Go to Settings.
c. Click on "Verify this URL".
3) You will be brought to google.com/webmasters/tools; type in your password and sign in.
4) a. There will be several options to verify your site, but ensure that the radio button for "Add a DNS record..." is chosen.
b. Now select your domain registrar (the company your domain name is registered at). If your company is not on the list choose "Other".
c. Follow the instructions to enter a DNS TXT record for verifying your site and then click "Verify".
If you properly entered the TXT record into your Registrar, the site will be verified. Otherwise, it will display a page stating your site is not verified.