You didn't specify the reportType you're using but I assume we're talking about KalturaReportType::MAP_OVERLAY?
The input for the objectIds field varies depending on the reportType. You are correct that in certain contexts, the required input is entry IDs, however, in the context of MAP_OVERLAY, the expected input is a country ID.
For example, when calling report->getTable() with $objectIds = null like so:
$reportType = KalturaReportType::MAP_OVERLAY;
$reportInputFilter = new KalturaReportInputFilter();
$pager = new KalturaFilterPager();
$order = null;
$objectIds = null;
$result = $client->report->getTable($reportType, $reportInputFilter, $pager, $order, $objectIds);
You'll get something like:
So, if you wanted to get only the records for UK, you could set:
$objectIds = 2;
Which would return something like:
Do let me know should you have additional questions,