kriging for point estimation

> I am new in geostatistics, so far what i read about kriging is that it is
> used for multiple point estimation. I need to interpolate value of a single
> point whose coordinates are given, by using at least six neighbors.
> The coordinates of my point are (100,75), and i find neighbors using this
> command.
>> coord=which((walk$x >= 75 & walk$x <= 100) & (walk$y >= 150 & walk$y <=
> 175));coord
> [1]  68  69 171 240 241 242
> These are row ids of neighbor points, I don't know how to limit kriging to
> only use these points for interpolation. Another problem is that the target
> point is not part of the data set and how I am suppose to mention that.
> i want to use this function
>> w.cal=walk[1:6,]
>> w.val=walk[272,]
>> k.val=krige(v~1,loc=w.cal,newdata=w.val,model=vmf)
>> k.val
>> summary(k.val)
> mydata.txt <http://geostatistics.forum.52north.org/file/n4022900/mydata.txt>  
> i attach my data set.
> *QUESTION*: Use kriging to estimate your target point by choosing at least 6
> nearest neighbors of it using 4 different variogram models and find the
> kriging variance for each. Compare your results in terms of minimum variance
> property.
>
> Anyone please help me out..i really need to figure this out.
>
>
>
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