https://www.epo.org/en/service-support/faq/myepo-services/online-filing-software/current-filing-and-submission-issues-1

A supplementary international search report (SISR) has been drawn up by a Supplementary International Searching Authority (SISA) under the PCT. Where do I indicate this on Form Euro-PCT(1200E2K)?

You can indicate that one or more supplementary international search reports were drawn up in the international phase by mentioning the relevant Supplementary International Searching Authority (SISA) or authorities in the Annotations tab on Form Euro-PCT(1200E2K). A copy of the supplementary international search report does not need to be filed, as it will be transmitted direct to the EPO by WIPO.

Note: If you qualify for a fee reduction for a supplementary European search, you can indicate this by editing the Reduction column in Fee selection under the Fee Payment tab.