Slitherine

Perhaps Rus' could be having ally of Khazar of Pecheneg in war 941 with Byzantine. As Wikipedia Rus'-Byzantine War(941) entry says

The Rus' and their allies, the Pechenegs, disembarked on the northern coast of Asia Minor and swarmed over Bithynia in May 941.

Same entry in Russian says(google translated)

According to the Cambridge document, Russia became dependent on the Khazars, however, the ancient Russian annals and Byzantine authors do not even mention the Khazars when describing events. [2] [3] .

So I think FOGII's Rus' 860-959 or Khazar 738-969 list could have ally of each other. Of course, Wikipedia is not primary source, so it may not be sure thing. But from the perspective of their geographic location and the era that Khazar and Byzantine are in hostile relation then Rus' raided Byzantine territory, it's quite probable that Rus' and Khazar formed sort of allies. Pecheneg may play a role as well.

The Khazars and the Pechenegi were two different groups, the former being a very heterogeneous confederacy and the most powerful economic entity (slave trade mostly) in the Black Sea littoral and north of the Caucases at the time. The latter were an Oghuz Turkic tribal organization. The Rus, which also started as a heterogeneous economic confederacy, were in direct competition with the Khazars, so it's very unlikely that they would/could have been allies.