generating a key field

for a key in my table I am appending RACT to a number..

So the key would be like this:

RACT100000000000000000000

I would like the next id to be:

RACT100000000000000000001
etc


Is there something in the table create that I could make that happen so that they keep adding one each time? Or is there a better way to do in in my t-sql code where I am inserting?