The only DL media consistently recommended is Verbatim and you are likely to be asking for headaches with the media you have. Additional problems with the RiData might be time before the disks degrade.
If I understand you question, you want Nero to recognize you are using DL media. Depending on the Nero program, you are likely to have a pull down menu as shown in the attachment. Select DVD5 for SL and DVD9 for DL.