Go to Settings > Editor > General > Smart Keys, then check the box that says Insert type placeholders in the documentation comment stub.

Go to Settings > Editor > General > Smart Keys, then check the box that says Insert type placeholders in the documentation comment stub.

Per the documentation:
If configured, the documentation comment stubs can be generated with
typeandrtypetags.
Following the link:
...
- In the Smart Keys page, select the check box Insert 'type' and 'rtype' to the documentation comment stub.
Note that the documentation has since been updated, the configuration guidance currently reads:
Enable documentation comments
Open the Editor | General | Smart Keys page of PyCharm settings ⌃⌥S.
In the Enter section, select or clear Insert documentation comment stub checkbox.
Then, scroll to the Insert type placeholders in the documentation comment stub option and select or clear the checkbox as required. Refer to the option description for details.
Once you have done this, put the cursor in a parameter name in the definition, activate the Smart Keys feature (Alt+Enter, by default) and select Specify type for reference in docstring. This will insert the appropriate comment line . Similarly you can put the cursor in the function/method name and select Specify return type in docstring.