Eclipse RCP: How to increase heap size for my RCP application?

I have an Eclipse RCP application where I use NSIS to generate the exe file for Windows. This RCP application is running into memory issue when processing big files and it will just fatally shut down. I need to increase the heap size. I read a few articles and it seems like the solution is to add the following arguments "-vmargs -Xms128m -Xmx512m". However, I'm not quite sure where to place this argument at.

I look at the installed project folder structure, it has the following structure:-

- configuration dir
|- ... some org.eclipse.* dirs
|- config.ini
- plugins dir
|- ... bunch of jars
- workspace dir
|- .metadata dir
 |- .plugins dir
  |- org.eclipse.ui.workbench dir
   |- dialog_settings.xml
   |- workbench.xml
- .eclipseproduct file
- myapp.exe <--- my RCP application
- uninstall.exe

How do I increase the heap size for my RCP application? Thanks.

The arguments should go, each on a line, in a file called myapp.ini, next to myapp.exe. They can be set up in the launching tab of the product definition file.