I am sorry but I dont think i understand your query completely. Have  you created a specification rule and wants to know which rule it can be associated with ? Or you have done something else. 

If you can elaborate it a bit then it will be easier for us to understand and reply.

Yes, I have created a specification rule for report definition requirements. Now which rule can that be linked to so the application document generates that linked rule along with the specification. I know that the specification is generated when generating the application document but how do you also get the report similar to screen catalog.

Still seeking an answer or comment on the above question.

You can associate specifications with most rule types to get a comprehensive view of the relationship between a specification and the rules that implement it. From the Implementations tab of an Application Specifications rule form, you can view existing implementations, associate specifications with additional implementation rules, and remove implementations.

• Open the Application Specifications rule form.
• Click the Implementations tab. This tab lists the implementation rules that are currently associated with this specification.
• Click the Add icon.
• In the Rule type field, enter the rule type or select one from the autocomplete list.
• In the Applies to field, type or select the Applies to class.
• In the Name field, type or select the rule name. The Description and Ruleset fields are populated based on the rule name.
• Click Save to apply your changes

The below links may help you further:
https://community.pega.com/sites/default/files/help_v721/project%20delivery/proj-associating-specifications-on-rule-forms-tsk.htm
https://community.pega.com/sites/default/files/help_v721/rule-/rule-application-/rule-application-usecase/implementation.htm