cant give reference to System.runtime.dll

if i give C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5.2\Facades path the studio shows yellow to and says reference is missing .

if i give C:\Windows\Microsoft.NET\Framework\v4.0.30319 this path then  visual studio 2015 shows multiple assemblies with equivalent identity have been imported.

i want to import

system.runtime.dll;

system.runtime.windowsruntime.dll;

Windows.winmd;

i want to do this to access "AppServiceConnection "