Symptoms

Whenever you attempt to navigate to the Designer site it does not resolve. No error message is shown other than a "page not found" page being shown.
 

Diagnoses

When the K2 Smartforms setup manager repair is run, the configuration is green but when trying to browse to the designer IE says page can not be found. Upon inspection of the environment that presents this error, a reinstallation of K2 was required on the server that hosted the K2 Designer (design) site. This was because the sever that is running the designer site needed to be reconfigured owing to the numerous web config and path directory errors we encountered when we tried to inspect the bindings within IIS.
 

Resolution

As a reinstall was required we used this documentation to reinstall Smartforms 4.6.9 to resolve the error:

http://help.k2.com/onlinehelp/K2smartforms/ICG/4.6.9/default.htm_Installation_and_Configuration.htm?TocPath=_____1

As well as more detailed information regarding a split configuration:

http://help.k2.com/onlinehelp/k2smartforms/ICG/current/default.htm_Design_Time_versus_Runtime_Sites.html_tracksearch=SmartForms split configuration"