Turn on “Auto-search” in top menu and run ProxyChecker at the limit clicking “Start”.

The software will automatically search sources with proxies and add them to the source list. If there is no unique proxy at the source it will be removed - as result you will get list of sources with proxies.

Proxy auto-search will stop automatically to prevent system overloading. You can change auto-search settings in the settings of ProxyChecker:

When it reaches necessary quantity of alive proxies turn off checking. Sort sources by count of alive proxies and remove ones where there are 0 or just a few proxies. You can select all sources at once (Clicking Ctrl+A in the sources) and selecting menu item “Change”, customize the process of checking.

When you have own base of alive proxies you don't need to turn on auto-search with each start - it is faster to let ProxyChecker use proxies from ready base. And only when count of alive ones there drops down you should use auto-search again.