As per PeopleBooks,

Understanding Search Records
The search record controls access to rows of data in a table, and its keys and alternate search keys appear on the search page as criteria. The search record might also contain logic to refine the search to secure rows of data—row-level security is implemented in this way.

The search record field populates the high-level, or level 0, key fields on a page. These key fields usually appear above a scroll area or bar or on the page, and they are typically display-only. The search record for a component might differ from the primary record definition for a page and might contain any number of search keys, but it must contain all of the keys for each main level 0 record for a page.

In ESS pages, you don't require a search page to be displayed as the page should take the current users details (specifically Employee ID) as search key and load the page.
In case of MSS, page should be loaded with the details of the employee chosen by manager.

Hi,
Could any one share views on below case ?
* on a specific search page (PS CRM 9.0) after entering search criteria if I press ENTER it should populate search results.
where as, it is not reacting to enter and when explicitly click on "search button" it is populating search results.

Thanks in advance for your thoughts...
- Srini

Just do the same search processing logic in the field change of the search key field