Things You'll Need
Instructions
Download RCTPatch.zip (or .exe) from the official site (see Resources). Unzip the file if necessary and run the executable.
Click "Yes" if the program has correctly determined the location of RCT.exe. Wait for a status report to say the patch was successful.
Open Rollercoaster Tycoon, then try to load a saved game. The patch works if saved games load as normal.