Bloodtypes gives us a look at how people act, their personality, courage yet also at how they live. Rinoa isn't a student at Balamb Garden, therefore her bloodtype isn't stated during the course of the game nor published by Square-Enix. Yet some people have been searched to put up a bloodtype on Rinoa and they do come with spectacular findings. The A type is most known to be given to Rinoa, because it has been published by Bandai, but let's look deeper.

Type A

Reserved calm, even tempered, introverted, sensitive to public opinion, responsible, reliable

even tempered and takes charge when others are in confusion

may be introvert or standoffish or shy

may feel nervous or ill at ease with others

sensitive to surroundings and others 

hesitant to change -may feel misunderstood

may shy from group-nature lover

prefers suburbs away from crowds

needs a private space for refuge 

may be accused of being pessimist because of fear of change

many are artists or creative types due to sensitivity

craves success

tasty served with any vegetable

Type B

Rational, pragmatic, organizer, individualist, egocentric, mind controls emotion

fixes, builds, creates- feels best when things run smoothly

The specialist-reads manuals and follows recipes

spends more time on groundwork

may focus on what they are doing and neglect other things

organized but may have clutter around them -clutter is practical personal things

energetic and has drive to reach goals

may be fanatic and work to “bitter end”

entrepreneurial but may not be flexible

not the best team player

rebels against structure of team -individualist may be volatile friend

may be called self absorbed -heightened sense of self

can be over dedicated to work

looks for matter of fact solution v sentimental one

may be accused of being cold or formal 

reserved in friendship

tasty served with chicken

Type AB

Laid back and outgoing, shy and assertive ,a blend of opposites

unpredictable, compelling

may seem to have calm exterior -introvert and extrovert

friends find them dependable but they may rebel if they are overwhelmed and then withdraw

generous on their own terms

unpredictable in social situations 

shy with some, bold with others

strong creative strain-artist/performer 

everything they do is compelling

drawn to psychology, astrology, fortune telling, spiritual, blood

good politician or diplomat

could be too flexible

good at spotting problem and averting it

likes city but may feel claustrophobic

home has elements that inspire thought and action

hermit and social, subdued and assertive

doer thinker- torn in many directions- successful at what they do

tasty with fresh vegetables

Type O

Sociable, energetic, extroverted, frank, realist, showy, flighty, generalist

makes friends easily-goes with flow and grasps opportunity-flexible

quick to start a project or chase an idea

when prospects are bad are first to bail out

may have short attention span

express strong emotions and may quickly take opposite view

declarations are deep but not always durable

classic entrepreneur -movers and shakers -move from place to place

express their emotions but can be swayed by other blood types

has an intrinsic elegance

sociable and showy

may be performer 

some good at crime

adapt to circumstance-words come easily to them

not self conscious- frank reveal inner feelings

ambitious, realist -material is more important than intellectual

may have problem with detail

tasty with "red" meat

Conclusion

Every bloodtype tells something about our way of life or how we feel. It's therefore not that easy to find out a conclusion of which bloodtype is perfect for a person. For this we have to find a bloodtype, which info fits that person the most.

It for sure isn't the A type as Bandai seem to claim, because she doesn't need a private space nor takes action in own hand, she is the type that prefers working around people she can trust and rely on. A would in my opinion be a close second to O. O has a markable talent in which tells us a sociable, energetic and even a frank nature. Rinoa does make friends easily with her laid-back attitude and does express her emotions quite easily.

A for me is something similar to how Quistis acts, so Rinoa can be seen better as Irvine, both have a O type then. Squall is the AB type, so because of the DNA switch this is left out, because AB can seen as a total opposite of O. B is under this circomstance a closer fit to A and O. Yet the B type is quite confusively then the O type to fit with Rinoa. 

I would say the O type.