I cannot find it anywhere, but it must be somewhere, because this is the reason I installend Piwik (and erased PhpMyVisites):
Wat URL is de url of the RSS-feed of the visitors during a certain time and how can I manage the preferences?
what do you mean exactly?
See the links at the top of Piwik
API: to get RSS links to last visits
SETTINGS: to go to preferencess
API: to get RSS links to last visits
SETTINGS: to go to preferencess
OMG. I am not a prof in information technology… 
I want at midnight a simple actualized rss-feed of the results of the past day, like phpmyvisits did.
So: the number of visitors and perhaps soms more information.