Labelling portions of a VCS root (perforce)

Hi -
  We're running TeamCity 8.0.6 and Perforce.  I have a build configuration that uses a portion of a larger VCS root, limiting the scope of files that get checked out via checkout rules specified in the Version Control Settings.  I'd like to apply a lable in perforce to only that subset of files used -- *not* the entire VCS root.  Is this possible?

For example, the VCS root references:
//depot/project/A/... //team-city-agent/A/...
//depot/project/B/... //team-city-agent/B/...

Then, in my checkout rules:
-:.
+:A

Yet, on a successful build, both A and B directories get labelled.  Is there a way to label only those files actually checked out via the checkout rules?

Thanks
phil