I worked a job where I would use roger in this sense. After I put in my 2 week's notice, a coworker told me that this actually annoyed my boss to no end. We used IRC extensively for communications, so I wrote an IRC bot that would reply "roger" to everything he said (along with some other sayings that annoyed him) and cron'd it to run a week after I had left.*
* The rest of the story is that I wrote two bots to say different things, but forgot that they'd trigger "roger" off of each other, so the end result is that I had two bots constantly spamming the channel with "roger". I guess I should have written tests!
IIRC, "Roger" came about in the early days of voice-radio communication as the old-style phonetic alphabet version of "R" (in the modern phonetic alphabet, "R" would be "Romeo") ; the single letter R was a "prosign" abbreviation used in Morse-code telegraphy (as • — • or dot-dash-dot) to indicate "received and understood." [0]
"Roger" meaning "Received and understood"... exactly what you're looking for "I acknowledge what you said". Sometimes used as "Roger that"
I learned this in the army and still use often in conversation or text.