How do I designate WebRoot scan on my external hard drive?

Hi tnatcsh
 
Welcome to the Community Forums.
 
I am afraid that you cannot do that at present if what yo mean by designate is to permanently set up WSA to scan the external drive.
 
If however you would like to manually scan an external drive (or any other for that matter) then you can either very do so in Windows Explorer by finding the drive, right clicking on it, and selecting 'Scan with Webroot; from the displayed context menu.
 
Alternatively you can set up a customer scan by clicking on the grea/cog symbol to the right of the PC Security tab in the main WSA panel, whic will open another tab, on which you will find in the bottom lefthand corner a button marked 'Custome Scan'.  If yo click on that then you will be taken to a further panel where yo can set up a custom scan, to include your external drive, and then run it...but unfortunately you cannot save and reuse that scan setting that you have just set up.
 
Hope that helps, otherwise do come back and we will see what else we can do for you.
 
Regards, Baldrick