From HRMS Assignment form we are going to invoke a custom OAF page which will show the supervisor details.Please follow the below steps to achieve this once custom OAF page development is done.

OAF page which shows the supervisor details.This page will accept a parameter PERSON_ID as parameter and displays the person's information.
Page Name         :  XXCUSTSupervisorInfoPG.xml
Controller            :  XXCUSTSupervisorInfoPG.java
AM                         :   PersonAM
VO                          :  SupervisorInfoVO 

Form function which refers to XXCUSTSupervisorInfoPG

Steps to call OAF through form personalization

1) Navigate to Assignment Form US Super HRMS Manager > People > Enter and Maintain - Choose Assignment.
2) Choose Help > Diagnostics > Custom Code > Personalize

We have to create a menu item under Tools. So we have to create a personalization 

Second thing is we have to attach a function call to above created menu item

The condition :ASSGT.ASSIGNMENT_ID IS NOT NULL is to prevent the page open when user clicks at first time.

3) Save and close the personalization screen. Close the entire form application. Open form servlet again. Now you can see the newly created menu item under Tools.

4) Click on Show Supervisor. You can see the supervisor details details in the custom OAF page.