How to have a custom value option other than the pre defined

Hi All,

I have requirement wherein user is provided with multiple radio buttons / check boxes from which user will do selection. There is an extra textbox provided labelled as other: [____________] .

I have master table called Qualification from which the Ratio buttons will be populated. Further have Candidate table in which the selected radio button value will go in Qualification column. I don't know how to implement the extra option in master table 'Qualification' and operations table that i.e. 'Candidate'.

Please direct if have posted question in a wrong section.