Summary
The purpose is this document is to show step by step to create/assign application component for process chain
Step 1: Create new process or open an existing process
Use Transaction RSPC
Step 2: Display Components and create/assign
press CTRL+F11 or [Menu-> Process Chain -> Attributes ->Display Components] or click icon 
on Application Toolbar
click icon 
to select component from below screen
Step 3: Create/assign Application Component
To assign application component select the application component from below screen then click icon
To create new application component click icon
or press F5 and enter required name and description
click icon
click
and click save icon, done!