How to use SEQUENCE in SQL 2012

Hi,

I have a fact table that is loaded with some 1 million of data)

Now I want to add one new "FactKey" column in this fact table so can u suggest whether to go for SEQUENCE creation will be helpful for this ?

How do I use SEQUENCE so that my existing fact table will be populated with this new "FactKey" column with sequential numeric values; and also when the new records will be inserted in fact table this "FactKey" will be incremented with the next values.

Can use of SEQUENCE accomplish this or I have to go with Identity column creation?

Thanks