Hi again Donna,
This site is about tracing ancestry as opposed to tracing living relatives. So, it is not the best forum for you for tracing your brothers or sisters.
IF the (*) Rennie we found in St Rollox born in 1934 is your dad, it appears he died in Scotland (Ayrshire) in 2001.
This is supposition, based on the fact that you think (*) was born in St Rollox. The death record will show who registered the death. Perhaps a son or daughter, or another living relative?
If you are sure his birthday was 14th August, spending the £12 for the birth record I mentioned would confirm whether or not it is the correct person, because it would show the exact date of birth. Then you could go for the death record?? - it's a starting point.
I wish you luck,
Dave
(*) Names removed to protect people's identity.