When you have mother shares and become entitled shareholder, they will send you a thick book/document, inside they have very detailed instruction on how to pay for your rights issue . 

Generally, two main method of paying  if your share is in CASH account ( that is CDP hold your share). First method  is old tradition of fill up form (ARE,etc) banker draft or cashier order, send mail with your own risk and reach CDP BEFORE the closing date and time. If your mail reach after their closing time and date, your application can be rejected.

Second method is very simple and is preferred , is by ATM. When using ATM, you need to key in correct information, select correct rights issue. I read some people key in wrong information or select wrong share and ended up missed his intentional of paying up for the rights.

Finally, if your mother share is in your CPF account, this one must be treated differently, you cannot use ATM for CPF account, you must contact your Agent Bank and give them instruction to apply on your behalf, they have much earlier closing date for paying for the rights. Make sure you follow their procedure so as not to miss the closing date/time.

NOL ??