Answer: The answer is "yes", the 892M will be able to perform that function. To test or evaluate your equation "strategy", you can download the IntelliPack Software from Acromag's website for free and use the 892M simulator to test click here.
Below are some notes/comments about the operation for your equation:
1. The 892M allows you to scale your inputs and output in actual "engineering" units. This means the "spreadsheet style" equation will perform floating point math on your scaled values. So, your "k" factor in your equation can be reflected in two places. First, you can simply change the scaled value for CH #2 (Input B)to be weighted differently than Ch #1 (Input A). Or, you can scale/weight both inputs the same and multiply Input B by any constant [ie; Output = A-((0.5)*B)]
2. For 0-10mA inputs and output, choose the standard 0-20mA ranges for the inputs and output. You'll be able to achieve a 0-10mA dynamic output by using scaling or thru your equation.