Hi Sachin! Thanks for posting in the community. Unfortunately this isn't possible with our UML functionality. If this is something you would like to see in our product in the future you can promote the idea to our produce team by filling out this form. I apologize for the inconvenience and thanks for your request!

There's a way around this UML limitation.  You can create a Text label and change it to italic.  Then put it near the top of your element that needs a stereotype.  Group the element and text label together. 

I'd rather see a stereotype feature as part of the UML this is a workaround.