Symptoms

Installed Visual Studio on a workstation but K2 for Visual Studio gives a warning that .NET 3.5 is required even though it is already installed. After skipping the .NET install and completing the K2 for Visual Studio install, opening k2 process on Visual Studio gives error "Could not load file or assembly 'sourcecode.workflow.design.form..."
 

Diagnoses

The .NET 3.5 and K2 SmartForm client tools must be installed in order for k2 Studio or k2 for Visual Studio to work.
 

Resolution

Get .NET 3.5 installed on workstation using DISM method (i.e. >dism /online /enable-feature /featurename:NetFx3 /All /Source:C:sxs /LimitAccess ). Then installing the k2 Smartforms client tools to resolve the issue.