Vibhor,

Do they have to be in the same field?   You can leave the reference field as it is and then add another field to your form that will display the short description from the knowledge article.   I use this on some fields that have references to the hardware asset tables so that I can display the serial number of the asset instead of just the asset tag number.

You just use the Configure -> Form Layout option from your form.   Select the reference field, click the button in the middle over the arrows to expand out the referenced table, then select the field on the other table you want to display.   I usually add a UI Policy to make that field from the other form read only so that people don't try to select the reference from that field.   As soon as you fill in the value for the reference field it automatically populates the other read only boxes.

I know that isn't exactly what you are looking for, but it might be a workaround if no one else has a better solution for you.

-Steve