I have a newly acquired 1990 k100 rs.
17900kms (almost through the break in period.)

I got is a couple of weeks ago stripped the fairings tank and all off the frames to get a good look and give her a thorough tooth brushing and to look things over.

All looked great, and super clean with the exception of the timing chain cover. There was sone evidence of oil leaking top and bottom. Not enough to say it's a problem but enough to ask if this is an area that needs to be watched as a rule.

The reason I as is that it looks as if the valve and bottom covers need to come off to renew. Additionally, it doesn't look as if the to cover has a gasket, only formed gasket via silicone. Is this true?

I ordered a manual just not shown up yet.

Thanks,

....Also low miles but 30 years almost. Any major points of wear, or breakage to to time that are typical?

There should be a rubber gasket between the head and the valve cover.  Have a look at the Max or A&S BMW parts fiches.  It's clearly a part of the assembly. Gasket sealer should only be used on the simi circle parts of the interface, as far as I know.

Both the valve cover and bottom end cover have rubber gaskets in the fishe but the timing cover does not show one (or rather 2).
The valve and bottom covers go on after timing cover, and the timing cover Mates with the timing cover. 

At least this is how it appears to me.

That's right the chain cover is just a 3Bond seal as are the others with the exception of head, cam cover and crank cover.

WelKome Canadabike, I just got home from being in TO for weekend!  

Permatex Ultra will do nicely for you.  Give it 24hrs to setup properly before you fill the motor with oil and fire it up.  Small oil leaks can be annoying but not catastrophic.  I still have a small one coming from this area on my '85 K100 after a major refit last winter.  I had the timing chain cover off more than once and still haven't found the exact source of the drip.  By June last year I just wanted to focus on riding and stopped worrying about it.  Mine has a few idiosyncratic issues but none of them keep it from running great and none of them are critical as I do keep an eye on all the vitals.

The rubber bits don't stand the ravages of time despite the low miles.  Replace the crankcase breather whether it appears to need it or not (Beemer Boneyard).  These bikes are a blast to get to know and the parts availability is excellent.