Normally the AttributeReprojector would be the one to use but it looks like your coordinates are malformed (let me guess, they're coming out of Excel?)

Fortunately, knowing that EPSG:28992 is the Netherlands RD projection, we know that the longitudes are in single digit degrees (in this case 4) and the latitudes are in double digit degrees (51)

So what I would do is:

1. StringReplacer to replace the . with an empty string, so you get 4438469 and 5186713
2. AttributeManager to divide the longitude by 10 and the latitude by 100 so you get 4.438469 and 51.86713
3. AttributeReprojector to reproject them from LL84 to EPSG:28992

And that should do the trick.

What he said! ^

Thanks, I used the wrong projection. I thought it was Mercator but it is LL84. About the rest, you are right. I already made good coördinates with string replacer and divided then.

LL84 did the trick. Thanks.