Alexander Halser from EC Software GmbH. has released an in-depth how to guide for preparing your Delphi VCL applications to support 4K displays. The guide talks about what the standard DPI in your Windows applications is usually set to (96 DPI), which versions of Windows support various DPI virtualization techniques, and changes you can make to your application manifest to make it DPI aware. Lastly it provides some source code in the form of a Windows message handler for scaling your application at runtime. There is a demo application included with the PDF how-to guide which you can test out and then implement yourself in your own applications. Specifically the guide discusses:
Head over and download the full 38 page guide for enabling 4K display support in your Delphi XE6 and XE7 VCL applications on Windows.