The official (English) site is http://en.rd-acs.com/ and the software downloads section is at http://en.rd-acs.com/down.aspx?TypeId=50074&FId=t14:50074:14
Note that if you change the language to Chinese (link at the top of the page) you may see a slightly newer version of RDWorks available. Here's a link to the Chinese downloads page, http://www.rd-acs.com/down.aspx?TypeId=50072&FId=t14:50072:14
The RDWorks file is a RAR archive (similar to a zip). You can use 7-zip to open it on Windows.