Right,,
The weight is an addition to your regulated take off weight for use of ass temp.
For example low pressure,you add to your actual tow to get your new regulated weight and then you find your max ass temp.
Concerning anti skid inop..you need to reduce your field/obstacle limit weight where the speeds are written.(you enter your rtow chart with actual OAT )and the weight where speeds are is your field/limit ,you substract 7950kg and it becomes your new dry field limit weight.
Then you need to correct your dry field V1 by an amount givenin your fcom based on field lengh required that you find in your dispatch perf manual..it should be about -12 kts or so.
For your initial question,as you enter your rtow table from left to right with OAT,you will see two weights,left column(climb limit) and rest(with speeds displayed) is the field/onstacle limit weight.
Your regulated take off weight(actual weight regulated for low pressure,wai,tai...) as you go up the ass temp becomes limiting when higher than climb or field/level off..
The highest mass with a reg weight below or equal to either lowest of climb/field becomes your max ass.
Your min ass in the other hand is based on your engine thrust tref.