Not quite sure what you mean by "Wrapper file". Do you mean you are attempting to export your application out from Pega 7? If that's the case, go to DesignerStudio > Application > Distribution > Package and you should be able to work your way through the wizard to get an export file.

Hi You mean you want to take the RAP for your application? or You want to check the RAP file which you have created.

If it is related to your RAP, 

For this you need to create RAP using below steps;

Importing your RAP to your Application:  DesignerStudio > Application > Distribution > Import now you can see all the rules which are mentioned in your RAP rule. 

Exporting your RAP to some location : Before this you need to create a RAP rule for your Application. Once you created RAP rule then you need to go with  DesignerStudio > Application > Distribution > Exprot and specify the location which you wanted to place your RAP.