HttpClient is not found in .NET 4.5

I had the same problem. After some digging around, i found you had to install this package and then add the reference to System.Net.Http for it to not complain!

Add a reference to System.Net.Http:

Start using vs2017, and encounter same problem, when creating Native + PCL, couldn't find the HttpClient, going to Nuget and get Microsoft.Net.Http solve my problems.