RAD PDF can be used with ASP.NET Core and the new ASP.NET 5!
While the RAD PDF installer contains RadPdf.dll, a .NET 3.5 and 4.x compatible library for use on your website, it also includes .NET Core and .NET 5 samples (also attached to this article) which link to the RAD PDF nuget.
Live Demo: https://www.radpdf.com/demo/net5/
If using the default Lite storage provider, the web control will require access to a RAD PDF System Service instance, but this is not necessary.
See sample source code on GitHub: