Symptoms
SalesForce Service Broker - .NET 2.0 SDK will not run on Windows Server 2012 R2.
Diagnoses
Blackpearl help doco (http://help.k2.com/onlinehelp/K2blackpearl/UserGuide/current/webframe.html_B2 Reference - Getting Started with Salesforce.html_tracksearch=salesforce) for "Getting Started with Salesforce" section 3 "Prepare to generate the Service Instance" advises that the .NET 2.0 SDK must be installed.
I have downloaded both x86 and x64 versions but neither will run on Windows Server 2012 R2 (double click or open file does nothing).
Resolution
Downloaded .Net 2.0 SDK from internal resource
Updated Registry Key pointing towards installation path to end with "/"