EDIT: As addressed by Beejamin, the phrases I provided display a lack of interest. That can equate to expressing a lack of experience, but you requested a response for a specific situation, so I'll focus on that.
"Versed", as you already used in your sentence is a really good way of expressing lack of knowledge. However I think you're looking for something more flexible. In that case I recommend the expression: "Not my strong side"
"Not my strong side" expresses a lack of knowledge in a subject, but also that you're neutral on it (as far as interest goes). It can be used quite broadly in a variety of situations, but you must also address the specific area in which you lack knowledge.
Person A: Can you help me fix my roof?
Person B: Sorry, construction work isn't my strong side.
Person A: Hey, I've got a virus on my computer! Do you know how to remove it?
Person B: Sorry, computers aren't my strong side.
Original post:
I would recommend also using the idiom:
"It does nothing for me."
That expresses 0 interest in the subject but in a friendly manner. However it's best used in less formal situations. In a spoken conversation, you may often hear it with "really" at the end. The meaning is the same:
"It does nothing for me really"
Another way of expressing a lack of interest in a subject, but in a polite manner, would be by using "keen".
"I'm not too keen on it" or "I'm not really keen on it".