First, you may using the RBS calculator for predict, but it will be more good if you using multipple allignment after your done in RBS calculator, actually you can use the other RNA sequence if there anyone have publish about your sequence or maybe anyone have publish and it still related or in heritance with your sequence. if you talk about bacteria's shine dalgarno (SD) RBS in bacteria there are many people that already publish about it and you can acces it. RBS actually have a pattern in sequence, that's the reason why i say you can using multiple allignment to find the RBS, with other sequence or sequence that related in heritance with yours. for try to find may using salis lab then you can compare with other site or other software to make more trusted. Sandeep K. Panda
If there is ribo-seq data available, you can check sequences for translation initiation start site from those. And use RNA-seq in parallel to compare the amount of RNA available. This would provide most reliable answer.