Backup a site and restore in multisite

As the title suggests, I would like to migrate a single web site into a site hosted on a multisite installation.
I was thinking of using snapshot pro and I would like to know:
1) If this is the right plugin to use or you have something different to suggest
2) What to select when exporting the site. Which tables ? Which files ?
3) How to import in the multisite, if there are any caveats or manual configurations I need to to.
Thanks for your help
Kind regards
Antonio