Hi, Rajasekhar,
Are you having issues with calling the Apex class in general, or with getting a response back? Have you seen the “Run Custom Apex Action” action type from within Skuid’s actions framework? If you annotate your Apex method with the @InvocableMethd annotation, you can then call it from Skuid. To do this, add a button to a page title or a global action to your table, set it to Action Type “Run Multiple Actions”, go to Actions, and add an action of type “Run Custom Apex Action”. You should then be able to find your invocable method and send in the parameters needed. You might have to reload the page builder to see the new invocable method. 
If that doesn’t work for you, I would check out Zach’s ideas from this post:
https://community.skuid.com/t/calling-apex-function
Does that help?
Emily
