I'm running Infrastructure Management and Performance Center. So you'll use REST to export the existing vendor cert. Use an editor (I used notepad++) to save it as your own.
You should look at the Power User Certification Guide, specifically, vendor cert.
The abbreviated process would be like:
Rename the Facet Type to your unique name, like replace cisco with your agency. You'll also need to edit the "DisplayName" value after the "Attribute" section of the file.
Add the new variable. I inserted the following after the first existing attribute in the file
<Attribute name="rttMonCtrlAdminTag" type="OctetString">
<Documentation />
<IsKey>false</IsKey>
<NeedsDelta>false</NeedsDelta>
<Source>1.3.6.1.4.1.9.9.42.1.2.1.1.3</Source>
</Attribute>
Then toward the bottom of the file, edit the existing expression definition to something like:
<Expression destAttr="Names">rttMonCtrlAdminTag + " : " + JitterPrecisionStatsIndex</Expression>
Then you'll use the REST client to import your new file.
And then, in PC, select Aggregator / Monitoring Configuration / Metric families
select the correct Metric family, like Response Path Test Jitter. Then select Vendor Certification Priorities and move yours to the top.
I don't work for CA, I don't have any Certification training. I stumbled around with this for a while and this is my best recollection of that path. It's been working on multiple installations for a couple of months now. Read the Power cert guide.