How to add Freely programmed F4 help in FPM form UIBB on button click?

Hi Experts,

We have a requirement to create an freely programmed f4 help(Webdunpro application) which should be shown while clicking on a button in Form UIBB,

I see that WD_VALUE_HELP parameter can be set to the component name and it displays the freely programmed help as well in the application.

However, am unable to call the webdynpro application from the button click .

Please help.