Is Forms 9.2 compatible with RIO 8.3?
Laserfiche Forms 9.2 requires Laserfiche Server 9.0 and higher. However, if you're just asking about Rio License Manager 8.3, then yes that can be used to license Forms 9.2.
What Laserfiche Server does Rio 8.3 come with "out of the box"...it was installed before my time, and hasn't been updated since 2/14/2014 - we don't currently have access to the server to check on that.
The version number listed as part of the Rio installation package name that you download from the Support Site, i.e. Laserfiche Rio 8.3.2, is the version of the Laserfiche Server that comes with it out of the box.
However, the Laserfiche Server itself could have been upgraded since the initial installation and deployment. As of 2/14/2014, the current release of Laserfiche was 9.1.0.
Regardless, it'd be best to find out the version of the Laserfiche Server being used.