[SalesForce] Related List Master Detail Objects

You named the Related List Label "Supplier Relations Escalation", so that is what it is called on the Page Layout. You can see it on the far right of your options.

You can use controller extension with StandardSetController. The getSelected() method of StandardSetController returns the selected records.

Visualforce

<apex:page standardController="ts2__Application__c" recordSetVar="selectedApplications" extensions="ApplicationExtn">
  <apex:pageBlock >
    <apex:pageBlockTable value="{!selectedApplications}" var="a">
        <apex:column value="{!a.name}"/>       
    </apex:pageBlockTable>
  </apex:pageBlock>
</apex:page>

Controller Extension

public class ApplicationExtn {
    public List<ts2__Application__c> selectedApplications {get;set;}
    private ApexPages.StandardSetController controller;
    private Set<Id> appIds = new Set<Id>();

    public ApplicationExtn(ApexPages.StandardSetController controller){
        this.controller = controller;
        selectedApplications = controller.getSelected();
}

For more information, refer StandardSetController Class